Barcelona continued to dominate possession in the latter stages and a late Cesc Fabregas header made it 3-0 to the Catalan outfit ahead of the second leg.
Here, Sports Mole dissects the 90 minutes of action between the two Spanish rivals.
On target 3
On target 9
Was the result fair?
Absolutely. It was going to take an almighty effort from the home side to secure something from the match and unfortunately they didn't have anywhere near enough to cause Barcelona problems. There have been criticism of these types of matches in Spain and despite just a three-goal separation, the gap in quality was exceptional.
5/10. Alaves should gain great credit for their character this evening. They struggled to find the elusive final ball throughout the 90 minutes but were not disheartened despite going for long periods without possession. Looking at the match with a wider perspective, they will be proud of their performance.
5/10. It was hardly vintage from Barcelona, but in truth it did not need to be. Tito Vilanova's side scored three goals without reply and will surely finish the job in the Nou Camp in the second leg. Villa and Iniesta both scored magical goals and it was typical Barcelona performance. However, they never had to get out of first gear, let alone second.
Sports Mole's man of the match
Andres Iniesta: The Spanish maestro was wonderful this evening. He scored a terrific goal and his all-round display was sensational. He didn't put a foot wrong.
Biggest gaffe of the match
Alexis Sanchez thought he had scored Barcelona's third in the second period when he converted from close range, only to see that the linesman had raised his flag. However, replays showed that the winger was at least a yard onside.
Jose Teixeira had a fairly straightforward 90 minutes of action this evening. He went unnoticed for large periods which is always a good sign for a referee. Neither team will have any complaints.
Alaves: Alaves return to domestic action at home to Sestao on Saturday as they attempt to remain top of the Segunda B division.
Barcelona: The Catalan outfit return to La Liga action at home to Celta Vigo on Saturday where they will attempt to make it nine wins from 10 league matches this season.