"I am not 100 percent physically and after consultation with my team, it was determined that I not play", said 37-year-old Federer.
Federer, who had been set to take on Stefanos Tsitsipas in the quarterfinals, bowed out with an injury to his right leg.
Despite that triumph, Djokovic's momentum has stalled somewhat in Italy, where he saved two match points to stay in the tournament with a comeback win against Juan Martin del Potro in the quarter-finals.
Both players had held serve in the second set before Djokovic, leading 3-2, broke Del Potro for the first time in the sixth game and went on to open up a 5-2 lead.
Konta, celebrating her 28th birthday, hit 42 winners against the 19-year-old Vondrousova and dominated the final set to clinch victory in one hour, 53 minutes.
Novak Djokovic has reiterated his admiration for Rafael Nadal ahead of the modern tennis greats' latest meeting, praising his rival's comeback from injury as they face off for the Italian Open title. Reigning US and Australian Open champion Osaka had earlier said she could not compete because of a problem with her hand. "Today those shots felt really slow and he had plenty of time to pass me when I was approaching to the net".
UAE energy minister hints at support for oil production cuts Iranian airlines also extensively fly in the Persian Gulf airspace although USA sanctions have reduced Iranian flights in general. Though impressive-looking, it has osteoporosis. "In fact, the U.S.is like World Trade Building that collapses with a sudden hit".
There were no chances for either player from then on, and the World No.2 dug in while serving for the set, recovering from 0-30 down and needing only one set point to move in front thanks to an unreturned serve.
The 20-year-old Greek advanced after Roger Federer - returning to the Rome clay for the first time since 2016 - retired with a right leg injury before their match.
"I did a lot of things well this afternoon. I've seen the physio", she said. "I played my best match on clay against Stan Wawrinka".
"So for me personally, every victory gives me confidence for the next one".
"In better news, I have returned to the practice court, and slowly building the strength back in my shoulder", she added with a picture of her lifting the Roland Garros trophy in 2014.
Karolina Pliskova beat Greek qualifier Maria Sakkari in the other semifinal, 6-4, 6-4.
Konta, ranked 42, fought back from a set down to seal victory on her fourth match point against Madrid Open victor Kiki Bertens 5-7, 7-5, 6-2 after nearly three hours to set-up a Sunday final clash with Pliskova.