Gabriel Diallo falls in opener, ending Canadian's Libema Open title defence

Canadian Gabriel Diallo, the defending champion, dropped his opening match at the Libema Open grass-court tournament Tuesday, falling 6-4, 3-6, 7-5 to France's Adrian Mannarino.

Diallo fired seven aces and won 73 per cent of his first-serve points, but Mannarino converted four of nine break-point chances in the two-hour, 30-minute match in 's-Hertogenbosch, Netherlands.

Diallo fell to 6-13 on the season and is projected to slide 30 spots to No. 84 in the ATP live rankings after failing to defend the title he won last year.

The Montreal native remains alive in doubles, where he and Poland's Hubert Hurkacz advanced to the quarterfinals with a 3-6, 6-4, 14-12 victory over India's Yuki Bhambri and Australia's Matthew Ebden.

An all-Canadian pairing of Montreal's Félix Auger-Aliassime and Denis Shapovalov, of Richmond Hill, Ont., was scheduled to open its doubles campaign later Tuesday against Petr Nouza of the Czech Republic and Austria's Niki Oberleitner.

Auger-Aliassime, the top seed in the men's draw, will play his first singles match Wednesday against the winner of Tuesday's match between Hurkacz and Hungary's Marton Fucsovics.

Also Tuesday, Victoria Mboko of Burlington, Ont., will partner with American Serena Williams for the legend's much-anticipated return to competitive tennis at the HSBC Championships at The Queen's Club in West Kensington, London, next week.

The women's doubles final is set for June 14.

It's the latest highlight in what has been an ascendant rise over the past year for Burlington, Ont.'s Mboko.

She was ranked 85th heading into the National Bank Open on home soil last summer, only to take down formerly top-ranked Naomi Osaka in the final to win the women's singles title.

Mboko is now the