Tottenham produced late goals from Harry Winks and Tanguy Ndombele to ensure the London outfit overcame a scare against a spirited Wycombe side to reach the FA Cup fifth round.
Wycombe, bottom of the Championship, had stunned their Premier League opponents when Fred Onyedinma slotted in the opener midway through the first half.
But Gareth Bale marked a rare start with the equalizer just before half-time, hooking in Lucas Moura's cross.
Tottenham upped the pressure in the second half, but Wycombe repelled numerous attacks as they looked set to take the game to extra time.
However, with Mourinho having sent on key players Harry Kane, Son Heung-min and Ndombele, the away side's quality eventually told as Winks curled home to give Spurs the lead with four minutes to go.
Ndombele ensured there would be no late drama when he finished from close range and then stabbed home a fourth in injury time to set Tottenham up with a fifth-round tie at Everton.
Spurs have already reached the final of the Carabao Cup and are also in the knockout stage of the Europa League.
They also host Liverpool in the Premier League on Thursday and Mourinho said not choosing to rest Kane, Son and Ndombele for that fixture highlighted his determination to win in every competition they play in.
