British No 2 Cameron Norrie bowed out in the second round of the Rotterdam Open after losing to Australian qualifier Christopher O'Connell on Wednesday.
Norrie, who defeated Spain's Roberto Bautista Agut in straight sets in the opening round, was edged out in two hard-fought sets against an in-form O'Connell.
World No 26 Norrie broke his opponent on his way to a 3-1 lead in the opening set, but was broken himself in the sixth game and lost a see-saw tie-break before dropping his serve again at the start of the second set.
O'Connell, who came through two qualifying matches and beat Valentin Royer in the first round, held on to his advantage to serve for the match when 5-4 up and, although Norrie saved five match points, the world No 119 sealed his win at the sixth attempt.
Stan Wawrinka marked another memorable moment in his farewell season, defeating 17-year-old Dutch lucky loser Thijs Boogaard in the first round.
The 40-year-old downed Boogaard 6-4 6-3 in a clash spanning more than two decades in age difference.
Wawrinka made headlines at the Australian Open last month by becoming the oldest man to reach the third round of the hard-court major since Ken Rosewall.
Victoria Mboko saved a match point before reversing the result of January's Adelaide final to defeat Mirra Andreeva 6-3 3-6 7-6 (7-5) at the Qatar Open.
The result was 19-year-old Mboko's third career top-10 win, and she advances to her second career WTA 1000 quarter-final following her surprise run to last year's Montreal title.
Mboko has now won 13 of her past 14 three-set matches since the final round of Wimbledon qualifying last year.
Top seed Iga Swiatek advanced to the quarter-finals with a three-set win over Australia's Daria Kasatkina.
The Pole sealed a 5-7 6-1 6-1 victory against Kasatkina to set up a meeting with former world No 3 Maria Sakkari, who beat France's Varvara Gracheva 7-5 6-0 to reach the last eight.
"It wasn't an easy match," said Swiatek. "Even in the second and third set I had to do a lot to win rallies against Daria.
"I think I gave her more chances. She used the slower surface here, and she was going for it more, compared to the last matches.
"I felt like I could do sometimes more in the first set. Yeah, I didn't really adjust well to the colder conditions and the wind. For sure it's a lesson for the next few days."
Novak Djokovic has withdrawn from next week's Qatar ExxonMobil Open in Doha due to fatigue.
The 38-year-old had been scheduled to make his first appearance since the Australian Open but will instead rest ahead of the North American swing.
Djokovic reached his 11th Australian Open final last month, where he lost to world No 1 Carlos Alcaraz in four sets.
Alcaraz and Jannik Sinner will headline the ATP 500 hard-court event in Doha, which begins on Monday, as the top two seeds.
Djokovic, who won back-to-back titles in Doha in 2016-17, owns a 15-3 tournament record.
He is next scheduled to compete at the ATP Masters 1000 in Indian Wells from March 1, where he has won five titles. A record he holds with Roger Federer.
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