STUTTGART, Germany — Montreal teen Felix Auger-Aliassime is still looking for his first ATP Tour title after a 6-4, 7-6 (11) loss to Italy's Matteo Berrettini in the final of the Mercedes Cup on Sunday.

Auger-Aliassime had his chances in the marathon second-set tiebreaker, but Berrettini fended off five set points before toughing out the win.

It was Auger-Aliassime's first tournament since returning a left abductor problem forced him to miss the French Open.

It was also the first ATP tournament on grass for Auger-Aliassime, who was seeded seventh in Stuttgart. The 21st-ranked rising star previously reached championship matches in Rio de Janeiro in February and the Lyon Open in May — both on clay.

Auger-Aliassime skipped last year's ATP grass season to play in Challenger Tour events on clay.

Berrettini won all 50 of his service games during the week in Stuttgart. He did not face a break point against Auger-Aliassime.

The Italian won his third ATP title and his first on grass.

Auger-Aliassime progressed to the final when Milos Raonic on Thornhill, Ont., withdrew ahead of their semifinal due to back problems.

Also Sunday, Denis Shapovalov of Richmond Hill, Ont., and India's Rohan Bopanna were defeated 7-5, 6-3 in the men's doubles final by Australia's John Peers and Bruno Soares of Brazil.