South Africa's Kevin Anderson advanced to the quarter-finals at Queen's for the first time after defeating Spanish fifth seed Feliciano Lopez 7-6 (12/10), 7-6 (9/7) in the third round on Thursday.
Anderson, seeded ninth, had never been past the last 16 in his previous four visits to the pre-Wimbledon warm-up event in west London, but he finally broke that sequence with an impressive victory over world number 17 Lopez.
The big-serving Anderson had seen off James Ward in the first round of the grass-court tournament and received an easier than expected second round win when Sergiy Stakhovsky was forced to withdraw with an injury in the final set.
At a towering 6ft 8in, Anderson can fire down serves with a potent combination of high bounce and fearsome power and, with his ground-strokes also improving, he has risen to 30th in the world rankings.
The 26-year-old won the second ATP title of his career at Delray Beach in February and he was in the groove from the start against Lopez.
Lopez has solid grass-court pedigree, reaching the Queen's semi-finals in 2010 and the Wimbledon quarter-finals last year, but he fell behind against Anderson as the South African broke for a 3-1 lead.
Anderson's nerve failed him as he served for the set and Lopez took advantage to break back.
It took an epic tie-break to settle the set and Anderson's composure held this time as he saved three set points before finishing it on his third set point.
The second set followed the same pattern and again it required a tense tie-break.
After missing his first match point, Anderson finally ended Lopez's resistance to set up a quarter-final clash with Bulgaria's Grigor Dimitrov.
Dimitrov ended giant-killer Nicolas Mahut's hopes of emulating his 2007 Queen's final appearance with a 7-6 (7/3), 6-4 victory.
Mahut had shocked world number four Andy Murray in the second round on Wednesday, but the Frenchman, who defeated Rafael Nadal en route to the final here five years ago, suffered a let-down against Dimitrov.
The 30-year-old admitted after beating Murray that he is keen to be known for more than his losing role in the longest match in tennis history against John Isner at Wimbledon in 2010.
Another long run at Queen's would have helped that aim but, despite breaking for a 4-3 lead in the first set, he couldn't finish off the gritty Dimitrov, who saved a set point at 4-5 with a lunging volley before converting his seventh break point of the game.
Dimitrov is regarded as one of the more talented youngsters on the ATP Tour and the 21-year-old underlined his potential with a dominant display to take the first set tie-break.
He pressed home his advantage with a break for a 3-2 lead in the second set and that was enough to see him through to the last eight in his first Queen's appearance.