Olivier Giroud came off the bench to score an injury-time header as Chelsea won 2-1 at Rennes to reach the knockout round of the Champions League on Tuesday.

Giroud has hardly played for Chelsea in recent weeks and this was just his eighth appearance in a frustrating season. But the France veteran made the most of a rare outing with an opportunistic winner in the 91st minute.

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Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Olivier Giroud came off the bench to score an injury-time header as Chelsea won 2-1 at Rennes to reach the knockout round of the Champions League on Tuesday.

Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Striker Sehrou Guirassy's 85th-minute and equally powerful header had given Rennes hope of pushing for a first-ever win in its Champions League debut season, as Chelsea conceded its first goal in Group E.

Chelsea's Callum Hudson-Odoi, center, scores the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Mount almost had a goal of his own in the 29th minute, only to be denied by a superb one-handed reflex save from Gomis.

Chelsea's Callum Hudson-Odoi goes to score the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Midway through the second half, Giroud came on for Tammy Abraham.

Chelsea's Mason Mount controls the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes has won only once in the past 10 games, having lost 3-0 in west London three weeks ago.

Rennes' Serhou Guirassy, left, waits for his teammates as Chelsea's Thiago Silva applauds after the opening goal of the English team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

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Rennes' Serhou Guirassy, foreground, and Chelsea's Thiago Silva fight for the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes' Serhou Guirassy, foreground, and Chelsea's Thiago Silva fight for the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

After Rennes again gave the ball away in midfield, goalkeeper Alfred Gomis saved forward Timo Werner's shot. But as the ball looped awkwardly up, the ever-alert Giroud reacted quickest to leap above static center half Damien Da Silva and planted a bullet header under the crossbar.

Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Striker Sehrou Guirassy's 85th-minute and equally powerful header had given Rennes hope of pushing for a first-ever win in its Champions League debut season, as Chelsea conceded its first goal in Group E.

The visitors took early control through right winger Callum Hudson-Odoi's slick 22nd-minute goal.

He ran onto Mason Mount's superb 50-meter pass, after the tenacious England midfielder got the ball off forward Jeremy Doku just outside the Chelsea penalty area.

Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Chelsea's Olivier Giroud, center, celebrates with his teammates after scoring his side's second goal during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. Chelsea won 2-1. (AP PhotoDavid Vincent)

Mount almost had a goal of his own in the 29th minute, only to be denied by a superb one-handed reflex save from Gomis.

Gomis became the Rennes No. 1 after Edouard Mendy was sold to Chelsea, and Mendy made a fine save to bat away his former captain Da Silva's header close to halftime.

Two minutes after the break, Werner had a goal ruled out for offside when he turned in Cesar Azpilicueta's cross.

Chelsea's Callum Hudson-Odoi, center, scores the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Chelsea's Callum Hudson-Odoi, center, scores the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Midway through the second half, Giroud came on for Tammy Abraham.

At the other end, Mendy denied his ex-teammates again when he saved from Guirassy and center back Gerzino Nyamsi in the last 20 minutes.

But he was powerless to stop Guirassy's header flying past him.

Chelsea's Callum Hudson-Odoi goes to score the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Chelsea's Callum Hudson-Odoi goes to score the opening goal of his team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes has won only once in the past 10 games, having lost 3-0 in west London three weeks ago.

In the group’s other game, Spanish club Sevilla also advanced to the last 16 with, with Munir El Haddadi also netting an injury-time goal in a 2-1 win at Russian side Krasnodar.

Chelsea tops the group and is level on 10 points with Sevilla, while Rennes is last behind Krasnodar with both on one point.

Chelsea's Mason Mount controls the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Chelsea's Mason Mount controls the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

More AP soccer: https://apnews.com/Soccer and https://twitter.com/AP_Sports

Rennes' Serhou Guirassy, left, waits for his teammates as Chelsea's Thiago Silva applauds after the opening goal of the English team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes' Serhou Guirassy, left, waits for his teammates as Chelsea's Thiago Silva applauds after the opening goal of the English team during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes' Serhou Guirassy, foreground, and Chelsea's Thiago Silva fight for the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)

Rennes' Serhou Guirassy, foreground, and Chelsea's Thiago Silva fight for the ball during the Champions League, group E soccer match between Rennes and Chelsea at the Roazhon Park stadium in Rennes, France, Tuesday, Nov. 24, 2020. (AP PhotoDavid Vincent)