Reigning Queen's champion Matteo Berrettini needed three sets to see off Denis Kudla as he reached the quarter-finals of the grass-court tournament on Thursday.
Berrettini won 3-6, 7-6 (7/5), 6-4 but the victory was anything but straightforward for the 26-year-old.
The Italian fell behind as his American opponent took a tight first set before Berrettini, beaten in last year's Wimbledon singles final by Novak Djokovic, edged a second set tie-breaker.
Berrettini then broke serve in the ninth game of the deciding set before he served out for the match after a draining two hours and 47 minutes on a sun-drenched centre court at Queen's, in south-west London.
World No 10 Berrettini will now play Tommy Paul in the semi-finals after the American's emphatic 6-1, 6-4 defeat of three-time Grand slam champion Stan Wawrinka.
The 37-year-old Wawrinka missed most of 2021 with a foot injury that required two surgeries and the Swiss player, now a lowly 290 in the world rankings, is trying to work his way back to form.
Berrettini's success means there are at least two seeds still involved in the Wimbledon warm-up event following Marin Cilic's win on Wednesday.
Rank outsider Ryan Peniston also remains involved, with the last British player left in the draw continuing a memorable week in front of his home crowd thanks to a three-set win over Argentina's Francisco Cerundolo.
The 26-year-old, playing in his first ATP Tour main draw, had already knocked out world number five and French Open finalist Casper Ruud on Tuesday.
And Peniston, a lowly 180 in the rankings prior to this week, was at it again with a 6-0, 4-6, 6-4 win in two hours over Cerundolo that saw him into the last eight.
Wimbledon wildcard Peniston survived cancer as a baby before going on to join the professional tennis ranks after learning his trade in France and at the University of Memphis.
It took Peniston just 20 minutes to complete a first-set 'bagel' on Thursday but Cerundolo put paid to hopes of a quick win by levelling the match before breaking at the start of the decider.
Peniston, however, hit back by winning the last three games in a row and he sealed victory with a winner down the line.
"I don't think I want to wake up from this any time soon," Peniston said on-court.