Djibril Cisse put visiting Lazio ahead in the fifth minute, but Robinho tied it in the 15th and Seedorf put the Rossoneri ahead three minutes later. Ibrahimovic entered in the 70th and scored in the 84th.
Aiming for its sixth title in the competition, Milan plays Serie A leader Juventus in the semifinals, while Napoli meets Siena.
VALENCIA, Spain (AP) — Valencia defeated Levante 3-0 on Pablo Piatti's two goals, setting up a semifinal with Barcelona in the Copa del Rey. Valencia eliminated Levante 7-1 total goals.
Piatti assisted on Aritz Aduriz's opening goal in the 25th minute and made it 2-0 five minutes later against Valencia's crosstown rival.
Levante played from the 72nd with 10 men after recent signing Oscar Serrano received his second yellow card for fouling Piatti. Piatti scored on a rebound in the 86th minute to complete the scoring.
Valencia will host Barcelona in the first leg next week. Athletic Bilbao visits third-tier Mirandes in the other semifinal.