The France international was at the heart of every positive thing at the Ramon Sanchez-Pizjuan Stadium as the Blues thumped the La Liga outfit.
Giroud made sure Chelsea had a flying start when he gave the visitors a deserved lead inside the opening eight minutes.
He then doubled Chelsea’s lead with a sumptuous goal nine minutes after the break, before getting his perfect hat-trick after meeting a cross from N’golo Kante on the 74 minute mark.
The 34-year-old wrapped up the Blues’ win with his fourth of the night from the penalty spot six minutes before the final whistle.
"Four goals at this level and the quality of the goals, individual aspects from Olivier [Giroud] and team aspects in the first half, from back to front the team were great, amazing solo performance from Olivier,” Lampard said after the game.
“Delighted with him, delighted with the team. This is a difficult place to come. There were moments in the first half where it was tough and we dealt with it.
"Olivier is reliable, full stop. Not just for us but his international goals for France, he's up there with great French individuals, he's got great statistics.
“I'm not too bothered about that in a way but I am bothered about what he gives us on the pitch. There couldn't be a team-mate there that the players are happier for because of the way Olivier is around the training pitch and in the games."
