Costume-wearing fans, boisterous crowds, exciting matches.

Old traditions were preserved when the revamped Davis Cup began a new era on Monday in Madrid.

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Russia's Andrey Rublev returns the ball to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Costume-wearing fans, boisterous crowds, exciting matches.

Russia's Andrey Rublev serves to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

The Croatian marching band roused the center court.

Croatia's team's captain Franko Skugor, left, talks with teammate Borna Gojo during their Davis Cup tennis match against Russia's Andrey Rublev in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

On court, two-time champion Russia, Belgium, and Canada took an early lead in round-robin play. Russia was ahead of defending champion Croatia after Andrey Rublev defeated Borna Gojo 6-3, 6-3. Belgium led Colombia thanks to Steve Darcis’ 6-3, 6-3 win over Santiago Giraldo, while Canada was beating Italy after Vasek Pospisil’s 7-6 (5), 7-5 victory over Fabio Fognini.

Colombia's Santiago Giraldo serves to Belgium's Steve Darcis during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

The new Davis Cup is the result of a 25-year partnership between the International Tennis Federation and Kosmos, a group co-founded by Barcelona soccer player Gerard Piqué, Shakira’s husband.

Belgium's Steve Darcis runs for the ball during the Davis Cup tennis match against Colombia's Santiago Giraldo in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

But it was a good start for the new finals, and the crowd atmosphere should ramp up on Tuesday when host Spain debuts with the top-ranked Rafael Nadal.

Belgium's Steve Darcis serves against Colombia's Santiago Giraldo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

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As the 18-team Davis Cup Finals got underway in its new weeklong World Cup-style format at the “Magic Box” tennis complex, fans were encouraged to provide atmosphere, and delivered.

Russia's Andrey Rublev returns the ball to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Russia's Andrey Rublev returns the ball to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

The Croatian marching band roused the center court.

Drum-beating Canadian fans lit up Stadium 2.

Dressed-up Belgians kept the crowd going in Stadium 3.

Umpires were made to work hard at all the courts by constantly asking for the fans to stay quiet before points.

Russia's Andrey Rublev serves to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Russia's Andrey Rublev serves to Croatia's Borna Gojo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

On court, two-time champion Russia, Belgium, and Canada took an early lead in round-robin play. Russia was ahead of defending champion Croatia after Andrey Rublev defeated Borna Gojo 6-3, 6-3. Belgium led Colombia thanks to Steve Darcis’ 6-3, 6-3 win over Santiago Giraldo, while Canada was beating Italy after Vasek Pospisil’s 7-6 (5), 7-5 victory over Fabio Fognini.

The teams are playing only two singles and a doubles in each tie, with the group winners advancing to the knockout stage later in the week.

The crowds were decent in numbers during the first matches, but the center court was mostly empty for the opening ceremony that featured an audiovisual show and performances by artists Alan Walker and Farruko. Colombian singer Shakira will perform in the closing ceremony on Sunday, all part of the modernization being promoted by the new organizers.

Croatia's team's captain Franko Skugor, left, talks with teammate Borna Gojo during their Davis Cup tennis match against Russia's Andrey Rublev in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Croatia's team's captain Franko Skugor, left, talks with teammate Borna Gojo during their Davis Cup tennis match against Russia's Andrey Rublev in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

The new Davis Cup is the result of a 25-year partnership between the International Tennis Federation and Kosmos, a group co-founded by Barcelona soccer player Gerard Piqué, Shakira’s husband.

The goal is to make the traditional team competition more attractive — and lucrative — by having all nations play at the same time and in a single venue. The change helped attract new sponsors and made it easier for top players to include the Davis Cup in their busy schedules. Prize money of nearly $20 million in total, rivalling those awarded in Grand Slams, also helped to attract players.

Critics, including some players, complained the new format would take away from the great partisan atmospheres seen in the head-to-head confrontations that were played out over four weekends through the year, for 119 years.

Colombia's Santiago Giraldo serves to Belgium's Steve Darcis during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Colombia's Santiago Giraldo serves to Belgium's Steve Darcis during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

But it was a good start for the new finals, and the crowd atmosphere should ramp up on Tuesday when host Spain debuts with the top-ranked Rafael Nadal.

Serbia’s Novak Djokovic and Britain’s Andy Murray will be playing on Wednesday.

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Belgium's Steve Darcis runs for the ball during the Davis Cup tennis match against Colombia's Santiago Giraldo in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Belgium's Steve Darcis runs for the ball during the Davis Cup tennis match against Colombia's Santiago Giraldo in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Tales Azzoni on Twitter: http://twitter.com/tazzoni

Belgium's Steve Darcis serves against Colombia's Santiago Giraldo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)

Belgium's Steve Darcis serves against Colombia's Santiago Giraldo during their Davis Cup tennis match in Madrid, Spain, Monday, Nov. 18, 2019. (AP PhotoBernat Armangue)