Defending champion Stefanos Tsitsipas and Olympic champion Alexander Zverev set Monte Carlo Semi finals date after eking out close wins in the quarterfinals.
After relatively comfortable journeys to the quarterfinals, both Tsitsipas and Zverev were made to work for their place in the Monte Carlo Semi finals.
Tsitsipas edged Diego Schwartzman 6-2, 6-7(3), 6-4 in an epic clash under the floodlights on Court Rainier III.
In an instant classic of quarter-final match that could have gone either way, Tsitsipas squandered a 5-2 lead in the second set, before rallying from 0-4 in the decider to triumph after two hours and 45 minutes.
After saving a break point in his final service game, Tsitsipas brought up the first of his two match points with a majestic diving drop volley.
Three points later, he celebrated after Schwartzman found the net to end a lengthy rally.
Tsitsipas looked down and out at 0-4 in the third set after losing nine out of 10 games from 5-2 up in the second set.
However, the World No. 5 then started to find his rhythm once again, hitting with greater width and topspin once again to triumph.
Tsitsipas is now two wins away from retaining his title in Monte Carlo, after he clinched his maiden ATP Masters 1000 crown at the event last year.
Standing in his way is Alexander Zverev whose match against Jannik Sinner lived up to the billing and then some by producing a Monaco classic over the course of three hours and seven minutes.
In a back-and-forth contest that saw 10 breaks of serve, Zverev finished strongest in a 5-7, 6-3, 7-6(5) victory to reach his second Monte Carlo semi-final.
Early breaks of serve were erased in all three sets, with Sinner coming from behind to take the opener and Zverev returning the favour in set two.
The German was twice pegged back in the third, and forced a decisive tie-break after missing out on a break point at 5-5.
Zverev edged a 7/5 tie-break in which half of the points went against serve, roaring with delight when a Sinner backhand found the net on match point.
