Keane heaped praise on the Argentina international for his ‘character and desire’, saying the former Ajax star has pride in his defending.
United defeated Nottingham Forest 3-0 away at the City Ground in the semi-finals first leg on Wednesday, thanks to goals from Marcus Rashford, Wout Weghorst and Bruno Fernandes.
Forest attackers were dealt with by the United’s impressive backline, with Martinez yet again putting in an impressive performance.
“He [Martinez] has got pride in his defending. He wants to defend.
“You’ve seen his character and his desire. He’s the kind of person you want to be in the trenches with,” Keane told Sky Sports.