All was going well for the US Open champion from Russia when he took the first set 6-4, having progressed to the fourth round with two straight-sets wins.

Medvedev then held a 4-1 lead in the second set, before Dimitrov, whose sole Association of Tennis Professionals (ATP) Tour Masters 1000 title came at Cincinnati in 2017, came roaring back to clinch it 6-4 and the third 6-3, recording his first victory over a top-two ranked opponent since 2016.

"He is such a tough player and competitor," Dimitrov said afterwards.

"Over the past year, I have played him a few times and haven’t been able to find a way.

"But today, I just felt something at 1-4 and I calmed myself down and started to take better decisions and started to control the pace of the game, which I really believed helped me.

"In the end, it was just very solid and smart play."

His opponent admitted that he considers Dimitrov a favourite to win the tournament based on his performance.

"Playing this level, I don't see him losing to anybody, but let's see the result," Medvedev commented.

Dimitrov will face world number 12 Hubert Hurkacz of Poland in the quarter-finals.

In the bottom half of the draw, world number three Tsitsipas had to win a second set tiebreak in order to keep his hopes alive, having lost 7-6 in the opening set to de Minaur.

He then eased through the third 6-2 to progress to a quarter-final against Georgia's Nikoloz Basilashvili, who overcame Russian Olympic Committee silver medallist Karen Khachanov in straight sets 6-4, 7-6.

The Tokyo 2020 champion and world number four Alexander Zverev of Germany took just over an hour to defeat French 14^th seed Gaël Monfils for the first time in his career.

He will play the hosts' last remaining men's singles representative Taylor Fritz as he upset Italy's Jannik Sinner 6-4, 6-3.

Argentina's Diego Schwartzman notched an impressive 6-3, 6-3 win against Norway's Casper Ruud, while Britain's Cameron Norrie overcame American Tommy Paul 6-4, 4-6, 6-2.

In the women's singles competition, the final two representatives of the United States were eliminated as Latvia's Jeļena Ostapenko and Belarusian Victoria Azarenka reached the semi-finals.

The 2017 French Open champion Ostapenko is in the last four of a Women's Tennis Association (WTA) 1000 event for the first time in three years after beating Shelby Rogers.

Her opponent found an early break in the deciding third set to take a 3-1 lead, but Ostapenko recovered to go through 6-4, 4-6, 6-3, hitting 51 winners in the process.

She will play Azarenka in the semi-finals as the two-time Indian Wells champion saw off Jessica Pegula 6-4, 6-2.

The women's singles competition has seen several of the biggest stars eliminated, with the top nine seeds all exiting prior to the quarter-finals.

Tomorrow's last-eight ties feature Germany's Angelique Kerber against Paula Badosa of Spain, seeded 10^th and 21^st respectively, while Tunisian 12^th seed Ons Jabeur faces the 18^th seed Anett Kontaveit from Estonia.

Norrie plays Schwartzman and then Dimitrov takes on Hurkacz in tomorrow's men's singles action.