Lewis picked up a strain in training and Pugh was placed on standby for the trip to Brighton.
Pugh pulled out of the squad to face Manchester United reserves but Michael Ricketts, Gylfi Einarsson, Dan Harding, Jermaine Wright and Ian Moore were all in the squad.
Kevin Blackwell said of Ricketts: "He has got to stay match fit because we have started the run-in to the end of the season now and I need to keep everyone as motivated and fit as we can. Dan Harding also needs a game, he pulled a hamstring the other week and we'll just see how he goes," he told the official Leeds United website.