Thomas Tuchel insisted he wants to continue as Paris Saint-Germain head coach amid growing pressure following the club's Coupe de France capitulation.
PSG also lost in the Coupe de la Ligue quarter-finals as pressure mounts on former Borussia Dortmund boss Tuchel.
However, Tuchel told reporters post-game: "Of course I want to continue!
"It's too early to take stock. I have to think for a few days. This is not an easy situation."
Goals from Dani Alves and Neymar put PSG 2-0 ahead inside 21 minutes before Presnel Kimpembe's own goal prior to half-time gave Rennes some hope.
Mexer's 66th-minute equaliser forced extra time, where PSG superstar Kylian Mbappe was sent off as Rennes eventually triumphed in the shoot-out.
"It's difficult to explain, also for me, because we made a good start to the game, very strong, very structured, with many qualities and many opportunities," Tuchel said.
"We had a lot of chances throughout the game. But after leading 2-0 it's hard to explain. For me it is a great disappointment to lose the second half 1-0. I have no explanation."