The Bayern Munich midfielder has struggled with a lingering ankle problem, but has been backed to star for die Mannschaft in their semi-final against Italy on Thursday
The influential midfielder has been nursing an ankle injury and misplaced several passes in the quarter-final win over Greece, leading to speculation he might be benched for Thursday's semi-final against Italy.
Writing in his column for German daily Die Welt, Magath, who was Schweinsteiger's club boss at Bayern Munich between 2004 and 2007, backed his former protege as a necessity in Joachim Low's team.
"If [Schweinsteiger] is injured, he cannot play. Otherwise I see no replacement for him," he stated.
"Neither Toni Kroos nor Lars Bender can adequately replace him as a player and above all as a personality. Schweinsteiger is needed."
Magath singled out Andrea Pirlo as the dangerman that die Mannschaft must watch out for on Thursday, and suggested crowding him out whenever the veteran regista is in possession of the ball.
"The key player of the Italians is Andrea Pirlo," he wrote. "He sets the pace and dictates the rhythm.
"But he can often fall back deep inside his own half. If he can be disrupted while receiving the ball, we would have achieved a lot."
Germany's last-four encounter with Cesare Prandelli's men will kick off at 20:45CET in Warsaw's National Stadium.