The Red Devils need just a goalless draw in the second leg of their last-16 tie at Old Trafford to qualify for the quarter-finals of the competition.
"Manchester United are favourites because they are at home, but Madrid are in good shape, playing well and come with a lot of confidence," he told Cadena Cope.
"United won this weekend 4-0 against Norwich too, though, I am sure Madrid will score a goal. Madrid played an impressive match against Barcelona and won 3-1, so I think the English team will opt for a more defensive game.
"[Sir Alex] Ferguson's team are physically stronger and although Barcelona have best XI in the world, the squad of Manchester United is much better."
The first leg of the tie ended in a 1-1 draw at the Santiago Bernabeu in Madrid last month.