'Red eye' Tsitsipas first Greek man to reach Roland Garros quarter-finals
The 22-year-old will now take on Andrey Rublev in a repeat of the recent Hamburg final which was won by the Russian.
Tsitsipas has now won 12 successive sets at the tournament having been two sets down to Jaume Munar in the opening round.
"I had a problem with my eye so that's why I had to call the doctor. It happened in my earlier matches too. It's still red and irritated," he explained.
On Monday, he saved three set points in the second set tiebreaker while frustrating 18th seed Dimitrov by saving the only three break points he faced.
"The tiebreak was where the money was," said Tsitsipas who fell in a five-setter to former champion Stan Wawrinka in the last 16 in 2019.