Fellow tennis star attended Carlos Alcaraz's Round of 16 match at Wimbledon

Rumors began circulating in June when Raducanu and Alcaraz announced they would be playing mixed doubles at the inaugural U.S. Open mixed doubles event.

"She's gonna be the boss," Alcaraz said of playing mixed doubles with Raducanu at the U.S. Open. 

Raducanu was then seen supporting him at the Queen's Club Championships. However, she has insisted she isn't dating the five-time Grand Slam champion.

"We're just good friends," she said in her news conference before Wimbledon.

Whether Raducanu is bluffing or not, Alcaraz certainly dazzled in his match against Rublev. He beat the Russian 6-7 (7), 6-3, 6-4, 6-4, hitting 41 winners and 22 aces. 

Alcaraz — the defending champion at the All England Club in London — has now won 18 consecutive matches at the grass-court tournament. He has also won 22 straight matches. 

Alcaraz aims to become the fifth male player to win three consecutive Wimbledon championships. The others are Bjorn Borg, Pete Sampras, Roger Federer and Novak Djokovic. 

Alcaraz's quest for a three-peat will continue in his quarterfinal match against Briton Cameron Norrie on Tuesday. 

Raducanu, meanwhile, has already been eliminated from the tournament. She lost to No. 1 seed Aryna Sabalenka 6-7 (8), 4-6 in the third round on Friday. 

At least, Raducanu has more time to catch Alcaraz's matches. Her "good friend" seems poised to dominate for the rest of the tournament.