The way Barcelona pressures its opposition is the key to the club's success, coach Luis Enrique said after a 6-1 demolition of AS Roma in the Champions League on Tuesday.

Last season's treble winner was at its breathtaking best with Lionel Messi back in the starting lineup, but Enrique focused on its work rate.

"We go into each game with the knowledge that we need to apply pressure, and the more that you do that then the better you get at it," the manager said after his team secured top place in Group E with a match to spare.

"We found it easy to find space and we had a lot of possession. It is not easy to keep pressuring, but this is what we are good at as a group. It is the key.

"Messi has fitted back into the side, I saw Suarez pressuring after 92 minutes, Neymar pressuring. It was the same as we have been playing before - all the team attacking and defending as a line."

Suarez scored twice and set up a pair of goals by Messi, who started his first game since picking up a knee ligament injury in September and looked hungry to get back on the scoresheet.

Gerard Pique and Adriano also tallied for Barca, while Roma's lone reply was from Edin Dzeko in stoppage time.

Enrique singled out Suarez for praise.

"He looks as though he has been playing for years at Barcelona and he is able to have a lot of influence with his work," said the manager.

"He is like a talisman because he brings so much positivity and intensity to our play and he is crucial when you consider, on top of that, his quality."

As well as winning its group, Barca leads La Liga by four points after crushing Real Madrid 4-0 in El Clasico on Saturday.

But Enrique believes there is still room for improvement.

"When you see your players enjoying themselves that is nice, but there are things to improve clearly," he said.

"Tomorrow when we are training we will look at ways that we can do things better.

"When you have 11 players there will always be ways that they can coordinate better."