WATCH: Jannik Sinner greeted with loud chants of his name at San Siro stadium while attending AC Milan's Champions League fixture vs Borussia Dortmund

Jannik Sinner's immense popularity shone through during the UEFA Champions League clash between AC Milan and Borussia Dortmund at the San Siro stadium in Milan, Italy.

Sinner capped off his remarkable season by leading Italy to their first Davis Cup title since 1976. The 22-year-old played a pivotal role in the triumph, guiding Italy to the final of the team event with impressive back-to-back wins over Novak Djokovic in singles and doubles.

In the title clash against Australia, following Matteo Arnadi's win over Alexei Popyrin in the opening match, Sinner delivered a commanding performance against Alex de Minaur. He secured a decisive 6-3, 6-0 win to seal Italy's triumph in Malaga, Spain.

Jannik Sinner has since returned to Italy to enjoy some well-deserved downtime during the off-season. Making the most of this break, the World No. 4 attended the Champions League group-stage game between AC Milan and Borussia Dortmund.

The impact of his recent Davis Cup heroics was palpable as Milan fans greeted the 22-year-old with enthusiastic chants of his name on his arrival at the San Siro.

Here's the video:

The Italian graciously acknowledged the passionate crowd with a wave, conveying his gratitude for the warm welcome.

However, AC Milan fans had little to cheer for during the game, as Borussia Dortmund advanced to the last 16 of the Champions League with a dominant 3-1 win.

Milan's solitary goal came from Samuel Chukwueze, while Marco Reus, Jamie Bynoe-Gittens and Karim Adeyemi scored for Dortmund.

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"Jannik Sinner backed up what he did against Novak Djokovic" - Lleyton Hewitt on Italian's Davis Cup heroics

Jannik Sinner lifts the Davis Cup trophy.

Despite Australia's loss in the Davis Cup final, team captain Lleyton Hewitt graciously lavished praise on Jannik Sinner for his remarkable performance in the prestigious team event.

Hewitt hailed the Italian for following up his thrilling win over Novak Djokovic with a stellar display in the final. He also humorously remarked that Sinner's proficiency on indoor hardcourts made life "tough" for the Australian players.

"Yeah, Jannik, he's played awesome all week. Yeah, the last few weeks, to be honest, last few months. So he showed why he's a top 3 or 4 player in the world at the moment.

"He backed up what he did yesterday against Novak and played extremely good tennis. I think the conditions and surface suit him perfectly, as well, which makes life pretty tough," he said in a press conference.

Alex de Minaur also expressed his appreciation for Jannik Sinner, echoing Djokovic's sentiments about the 22-year-old riding an astounding wave of confidence. The Australian praised Sinner's high level as "seriously impressive."

"I think probably Novak (Djokovic) said maybe a week ago, Jannik (Sinner) is riding this amazing wave of confidence," De Minaur said. "He’s seriously impressive at the level he’s showing."