The ex-Spain international has highlighted the importance of the prolific attacker in the so-called big games, while also praising Andres Iniesta
After coming in for some heavy criticism in recent weeks for some allegedly below-par displays following his return from a hamstring injury, the Blaugrana No.10 netted twice in a hard-earned 4-1 victory over Sevilla at the weekend that propelled the Catalans back to the top of the Primera Division.
Milla felt that the Albiceleste ace's display at the Ramon Sanchez Pizjuan simply proved what while form is temporary, class is permanent.
"When the going gets tough, Messi will come up with the goods, just like he's always done," the ex-Spain international is quoted as saying by Marca.
"Messi is still getting into the swing of things. He has been struggling to get going, but he's an instrumental player and Barcelona needs him right now."
Milla, who also wore the Real Madrid jersey during his active career, then went on to discuss Andres Iniesta's contribution in recent weeks, stressing that the attacking midfielder remains instrumental for Barca.
"After his fitness issues, it's normal for Iniesta to be gradually eased back into the fold," he mused.
"He looked better again versus Sevilla and is an instrumental player when he is on song. He gives the team a lot of breathing space when he links up with Messi and Xavi."
Iniesta has netted once for Barcelona in 21 Liga appearances this season.