"I think we did more than okay", he commented.
Regular number one De Gea continues to be linked with Real Madrid, but Mourinho insisted he is keen to keep the Spaniard.
He again fielded an under-strength XI in Wednesday's 0-0 draw at Southampton, omitting Marcus Rashford, Michael Carrick, Ander Herrera, Paul Pogba and David de Gea, as goalkeeper Sergio Romero's performance earned them a draw.
Manchester United manager Jose Mourinho has launched a new attack on the Premier League by accusing them of hindering his team's bid for Europa League success.
Asked when Manchester United fans can expect to see De Gea in a Red Devils shirt again, Mourinho told Sky Sports on Wednesday night: "David?"
And Mourinho said that, despite an imperfect display, he was pleased with his side's desire to prove themselves ahead of the Ajax clash - signalling out Romero for individual praise.
"I think all of them gave me positive feelings".More news: DOJ names former Federal Bureau of Investigation head Robert Mueller to lead Trump-Russia probe
"In any country in the world the match would be Saturday, because Sunday we are sixth, doesn't matter what, and Crystal Palace are safe", said the Portuguese. "For this club we need the trophy".
"We have the Argentina national goalkeeper and the Spanish national goalkeeper - two of the best national teams in the world", Mourinho said.
Despite the hard-fought draw, in which Southampton would have won but for the brilliance of United's stand-in goalkeeper Sergio Romero, manager Claude Puel remains under pressure. "They showed me that they want to be in the final, they want to be an option".
United have now drawn four of their last seven games in all competitions following this stalemate on the south coast.
"But it's a shame and I think to have had this situation with this opportunity and good play with many possibilities and opportunities is good work for the next game and of course to find the clinical edge".
"He played 90 minutes in the last game [against Southampton], so probably not". I never saw. It's just a lost battle; we have to accept the way it is.