The league leaders beat Chelsea 2-1 at home in their last 16 first leg on Wednesday with a battling display, a performance they must reproduce for the trip to Udine given Walter Samuel, Ivan Cordoba, Sulley Muntari and Esteban Cambiasso are suspended.
Coach Jose Mourinho is also banned from the dugout for three games following the controversy at last weekend's 0-0 draw with Sampdoria, where the Portuguese made a gesture indicating he was handcuffed after having two players sent off.
That draw, their third in a row, and AC Milan winning their game in hand 2-1 at Fiorentina on Wednesday has cut Inter's lead to four points.
Mourinho said, however, that the Chelsea win would boost his men in their quest for a fifth straight scudetto.
"They showed mental strength. I think it will make a difference for the future," Mourinho told reporters.
The former Porto and Chelsea manager also rejected accusations that he was too controversial, saying Italian football needed to examine itself given the 2006 match-fixing scandal.
"I arrived in Italy honest and I will leave Italy honest," he said.
Milan and in-form Ronaldinho host struggling Atalanta on Sunday.
Third-placed AS Roma, five points behind Inter, could again be without injured strikers Francesco Totti and Luca Toni for the tricky trip to fifth-placed Napoli.
Forward Mirko Vucinic, however, has consistently proved he can handle the load on his own during Roma's great run of form.
Juventus, who have climbed back up to fourth after two laboured wins, entertain Palermo in Sunday's late game hoping to put more distance between themselves and the sixth-placed Sicilians.
