Danny Welbeck's first-half header gave the Red Devils a precious away goal, but United old boy Cristiano Ronaldo also left his mark on the meeting with a brilliant equalising header.
Analysing the match on Sky Sports 2, Mourinho said: "Nothing new. Not a surprising match, not a surprising result.
"I think basically (it was) what I was waiting for, which is everything very open for the second leg. As I was thinking, I think this will go to the last minute."
Asked if the meeting had resembled a game of chess, the Portuguese replied: "For them - not for us. They changed their way of play.
"They had the block very, very low in the second half. I think Rio (Ferdinand) and (Jonny) Evans - they didn't put one foot in our own half. They were waiting for a set-piece or a counter-attack.
"They defended well and the result is open. If you ask me percentages, I don't change one single number - 50/50."
Mourinho remained upbeat about his side's chances heading into the Old Trafford rematch on March 5.
Asked whether the draw handed the advantage to United, he replied: "No. We can score more than one goal there."
He added: "They had two big chances in the second half, but chances out of context because we were chasing the game and they were just defending.
"This is the Champions League and there are two matches, home and away. They did their match and they did it well."