A day after Justin Engel became the youngest tennis player in 40 years to reach a men's tour quarterfinal on grass, his run at the Stuttgart Open ended with a loss to Felix Auger-Aliassime on Friday.

The 17-year-old German gave former U.S. Open semifinalist Auger-Aliassime a tough fight in the first set before the Canadian took a 7-6 (3), 6-3 win.

Auger-Aliassime next plays second-seeded Taylor Fritz in the semifinals. The Canadian's victory keeps up a record of reaching the semifinals all three times he's played in Stuttgart. He was runner-up in 2019 and 2021.

Engel's upset win over U.S. player Alex Michelsen on Thursday made him the youngest player to reach the quarters of any tour-level men's grass-court event since Boris Becker won Wimbledon as a 17-year-old in 1985.

Engel this week also became the second-youngest player since 1990, behind Rafael Nadal, to have won a match on all three surfaces — grass, clay and hard-court — on the tour.

Canadian Diallo advances

Montreal's Gabriel Diallo fired 19 aces to beat No. 3 seed Karen Khachanov of Russia 7-6 (6), 6-4 on Friday at the grass-court Libema Open.

The Canadian won 74 per cent of his first-serve points and saved four of five break chances.

He took the opening set in a tight tiebreak before Khachanov responded with a single break in the second.

Diallo broke early in the third and never faced another break point.

The 23-year-old is projected to rise to No. 48 in the ATP's live rankings — the first top-50 showing of his career.

Diallo will face No. 2 seed Ugo Humbert of France in Saturday's semifinal after Humbert beat No. 7 seed Nuno Borges of Portugal 6-1, 6-4.

In the women's competition, Bianca Andreescu of Mississauga, Ont. lost her bid to advance to the final four after dropping a 6-2, 6-4 decision to Romania's Elena-Gabriela Ruse in the quarterfinals.

Andreescu fell behind 5-0 in the first set and couldn't recover. The 2019 U.S. Open winner was looking to advance to her first semifinal of the season.

It was Ruse's second straight win over a Canadian after she beat Carson Branstine in the second round.