Roger Federer crashed out of the Internazionali BNL d'Italia with a third-round defeat to an impressive Dominic Thiem on Thursday.
World number two Federer expressed doubts that he would be bit to face 13th seed Thiem in Rome after beating Alexander Zverev on his return from injury on Wednesday.
The 17-time grand-slam champion was hampered by a back problem after recovering from knee surgery and the legendary Swiss was clearly not 100 per cent as he was beaten 7-6 (7-2) 6-4 in just an hour and 18 minutes.
That should take nothing away from world number 15 Thiem, who fully deserved his victory after producing a classy performance in the Eternal City to set up a quarter-final against Kei Nishikori or Richard Gasquet.
There will be concerns over whether Federer, who said he has "no chance" of winning this tournament for the first time after beating Zverev and made 34 unforced errors against Thiem, will be fit to play in the French Open but he will at least have further time to recover.
Federer was up against in it in the second game when a sprightly Thiem earned a break point, but the third seed produced three booming aces to hold.
Thiem found himself a break down when a magnificent Federer backhand put him 0-30 before the world number 15 put a backhand long to go 3-2 down, but the Austrian responded by levelling at 3-3.
It was Thiem who took charge in the tie-break, showing great defence and conjuring a sublime backhand which Federer had no chance of returning.
Thiem sensed his chance to cause an upset and broke again to lead with another sizzling backhand and there was no way back for Federer.