After Bayern defeat, we realised things has to change: Sergi Roberto reflect on Barcelona 8-2 defeat

The pre-season hard work has paid off in the Villarreal and Celta wins, according to the 28-year-old.

"It was very important the ambition we showed even with a man down. We still went forward, we still looked for goals, we defended as a team, we played with a lot of desire, we’ve shown we’re really up for things," Sergi Roberto said after Barcelona's win over Celta on Thursday.

"I think we realised after Bayern that things had to change. We’ve worked really hard in pre-season, the team has looked good in training and you saw that when we went down to 10 men and were still fighting at the end."

Barca is yet to drop points or even concede a goal in this La Liga season so far as Ronald Koeman's men defeated Villarreal (4-0) last weekend before beating Celta (3-0).

Lionel Messi played a huge part in both victories and Roberto is delighted with the Argentine's stay at Camp Nou despite this summer's exit saga.

"Leo looks plugged in, he’s playing for the team, he’s working hard and it’s great he’s still with us and has so much desire," the 28-year-old added.

The Catalans return to the league action in a home encounter with Sevilla on Sunday.