British wildcard Ryan Peniston says he "does not want to wake up anytime soon" after fighting back to beat Francisco Cerundolo and reach the Queen's quarter-finals.
The world number 180, who stunned top seed Casper Ruud on Tuesday, overturned a break deficit in the deciding set to beat the Argentine 6-0 4-6 6-4.
The 26-year-old is making his first appearance at an ATP Tour event.
"I slept great last night and I'm going to sleep even better tonight," he said.
Peniston, the last remaining Briton in the singles draw, looked to be heading for the exit after being broken early in the third.
However, a battling game at 4-3 down resulted in him retrieving the break as he reeled off the final four games to win.
He will face either Serbia's Filip Krajinovic or American Sam Querrey next.
"I just took a lot of confidence from the last match against Casper and came out guns blazing," Peniston said in his on-court interview.
"Then the second set didn't go to plan - Francisco is a great player - and then I just managed to fight in the third set and got over the line.
"I'm pretty happy about it."
Peniston has been given a wildcard into the Wimbledon main draw, which begins on 27 June.
Peniston has now beaten a top-five and a top-50 player in his first two matches on the senior men's tour.
He started the match in ideal fashion, breaking Cerundolo at the first opportunity as the world number 46 struggled for rhythm.
The first seven games of the match went Peniston's way before Cerundolo got on the board, and the Argentine then broke in the next game to take the lead for the first time.
Peniston had his opportunities in the second set but missed all three of the break points he created and often overhit in key moments.
He started the deciding set strongly, racing to a 40-0 lead, but he began to cut a weary figure as he lost the next three points and subsequently dropped serve.
However, cheered on by an increasingly vocal crowd in west London, Peniston kept within touching distance of Cerundolo, before breaking back when his opponent sent a backhand into the net.
The Briton then held firm in the next two games, roaring to the crowd and pumping his fist as he sealed victory with a forehand winner.
Berrettini battles through
Earlier, defending champion Matteo Berrettini survived a scare to beat Denis Kudla and reach the quarter-finals.
The Italian, champion at last week's Stuttgart Open, fought past the America 4-6 7-6 (7-5) 6-4 in two hours and 47 minutes.
The world number 10 saved five of the seven break points he faced to set up a meeting with another American, Tommy Paul.
Paul beat three-time Grand Slam champion Stan Wawrinka 6-1 6-4 to secure his place in the last eight.
American Paul had previously never won an ATP grass-court match before but has now claimed back-to-back wins over Wimbledon semi-finalist Denis Shapovalov and Switzerland's Wawrinka.
Top seeds Salisbury & Ram out of doubles
In the doubles, Britain's world number one doubles player Joe Salisbury and American partner Rajeev Ram - the top seeds here - lost 7-6 (10-8) 6-2 to Briton Lloyd Glasspool and Finland's Harri Heliovaara.
Meanwhile, defending champion Gordon Reid has withdrawn from the singles wheelchair event after rupturing a tendon in his wrist.
The Briton picked up the injury during the French Open, where he and Alfie Hewett won their 10th Grand Slam title in a row in the wheelchair doubles.