The Serb, three-times a Wimbledon champion, appeared distraught after his quarter-final defeat by unseeded Marco Cecchinato in which he was treated for neck pain.
'But I definitely need to take some time off now to kind of reassess the whole clay court season, to be honest.
In an epic fourth-set tie-break, Djokovic saved three match points but wasted three set points as Cecchinato became the lowest-ranked man to make the last four in Paris since 100th-ranked Andrei Medvedev in 1999.
In the second set, Verdasco broke in the sixth game and won four consecutive games, dropping just four points to claim the second.
But all eyes will be on Monday's showdown between Serena Williams and Maria Sharapova, with the latter trying to end an 18-match losing streak to her bitter rival.
"I just could never turn it around out here".
No. 10 Sloane Stephens finds herself up against No. 14 Daria Kasatkina, who lost some rest after Sunday's match was postponed in the second set due to darkness.
Cecchinato, who described his sporting heroes as the Brazilian footballer Kaka and Marat Safin, is the first Italian man to reach a Grand Slam semifinal since Corrado Barazzuti made the last four here in 1978.
After a tight opener was settled by a tiebreak, Verdasco steamed ahead and Dimitrov simply had no answers as he fell 6-7 (4-7) 2-6 4-6 in a match lasting just under two-and-a-half hours - something he suggested has always been the case when playing in the French capital. This will be Zverev's first quarterfinal match in a Grand Slam, so Thiem edges him in experience. It was a second-straight five-setter for the 21-year-old, who also had to battle past Dusan Lajovic in the previous round.
"I know how to handle a Grand Slam now, how... to get that deep in such a tournament, and I think everything gets better with experience".
Zverev, considered among a select few capable of dethroning defending champion and French Open king Rafael Nadal, had to do it the hard way as he was on the right side of a 6-2, 3-6, 4-6, 7-6, 7-5 scoreline.
"Unfortunately I have to continually stop here, I mean, the same time", Dimitrov told reporters.
"To be able to win that first set and get ahead was crucial".
"So being and talking like this after the match is for me something normal for a great champion".