Nick Kyrgios has prevailed over former world No.1 and close friend Andy Murray in a three-set epic at Queen's Club in London.
Murray was returning from an almost year-long injury lay-off and looked to be in good touch after taking the first set.
Kyrgios was serving to stay in the match in the second but bossed the tiebreak and then took the decider after the Scot double-faulted to win 2-6 7-6 (7-4) 7-5.
It was Kyrgios' first victory over the two-time Wimbledon champion at his sixth attempt and also his first singles victory in west London.
He sent down 18 aces and was broken four times from 11 attempts, winning three from 11 on Murray's serve.
"Obviously we are good mates and it was great to see him back and healthy," Kyrgios, who lost to Roger Federer in the semi-finals on grass in Stuttgart last week, said.
"I asked him at the end if he felt healthy and he said yeah, which is the main thing.
"It was nice to finally get a win over him but I can't really count it. He came out really good and I kind of expected that. Personally I feel good. I was out for two and a half months so I'm feeling good."
Earlier, former world No.1 Novak Djokovic bounced back from his French Open disappointment with a straight-sets demolition of Queenslander John Millman.
Djokovic, who lost to Italian giant-killer Marco Cecchinato in the quarter-finals at Roland Garros earlier this month, was rampant in a 6-2 6-1 win.
Millman raced to a 40-0 lead in his opening service game but that was as good as it got for the 29-year-old. Djokovic got the first service break in the fifth game to go 3-2 ahead before taking another two games later.
The second set progressed in much the same fashion, Djokovic going up a break with the opening game before a marathon fifth game also went the way of the Serb, giving him a 4-1 lead.
"It was a good match," Djokovic said. "I can't really talk about too many negatives.
"The focus was there, right intensity every shot. Every shot was working beautifully."
Djokovic will next face Grigor Dimitrov, who survived a tough first-round workout against Bosnia's Damir Dzumhur.
The 27-year-old Bulgarian was edged out in a second-set tiebreak but eventually prevailed 6-3 6-7 (7-4) 6-3, sealing victory with an ace.
There were also first-up wins for Jeremy Chardy, Julien Benneteau and Argentina's Leonardo Mayer, who upset South African third seed Kevin Anderson.
Milos Raonic also progressed but later withdrew due to a shoulder injury.