Leganes were angered by Luis Suarez's goal being allowed to stand on Sunday, but Ernesto Valverde says the officials made the right call.
Chelsea and Arsenal will be pleased with their draws in the Europa League but five-time winners Sevilla face a tough trip to Lazio.
The draw for the round of 32 in the Europa League was made on Monday, throwing up some mouthwatering ties.
Celtic were able to breathe a sigh of relief as they advanced from Group B in the Europa League despite losing to Red Bull Salzburg.
A mistake by Allan McGregor led to Rapid Vienna's winner as Rangers lost 1-0 and went out of the Europe League at the group stage.
AC Milan boss Gennaro Gattuso insisted there are no easy games in the Europa League after a nervy encounter with unheralded Dudelange.
Olympiacos secured progression into the Europa League knockout stages at AC Milan's expense thanks to a 3-1 victory in Athens.