The Argentine made no mistake from the spot after Danny Welbeck had been felled by Peter Ramage, but it was far from a vintage united performance. Ji-Sung Park hit a post but United side failed to turn their dominance into chances.
United totally dominated possessions but - with Rooney, Berbatov and Ronaldo rested - attacks constantly misfired.
Last News: Owen Hargreaves will be out for the rest of the season with a knee problem.
Tevez, who has regularly been left out of the United starting line-up in recent weeks, made no mistake from the spot, sending Cerny the wrong way.
It was en effort from visitors at the end of the match, but few could argue that United deserved the win and to go through to the last eight of the competition.
United line-up: Kuszczak, R. Da Silva, Neville (Vidic 89), Evans, O'Shea, Gibson, Possebon (Welbeck 72), Anderson, Nani, Tevez, Park. Subs not used was: Foster, Carrick, Manucho, Cleverley, Gray.
Goals: Tevez 76 (pen).
Referee: Phil Dowd.
Source: BBC Sports.
Thanks for reading!