Luis Enrique said there was room for further improvement after Barcelona continued its formidable hot streak with a 6-1 demolition of Roma that sealed top spot in Champions League Group E.

Barca followed up Saturday's resounding 4-0 Clasico triumph at Real Madrid with another irresistible display as its Serie A opponents were put to the sword at Camp Nou.

Lionel Messi marked his first start since suffering knee ligament damage in September with an 18th-minute goal shortly after Luis Suarez opened the scoring.

Suarez and Messi completed their respective braces either side of halftime, and Gerard Pique and Adriano also were on target before Edin Dzeko, who had a penalty saved, registered the merest of consolations for Roma in injury time.

"When you see your players have fun out on the pitch, you’re happy," Luis Enrique told a post-match news conference. "We take every game with the seriousness and necessity to know that in the most important stretch of the season it will be important to create this kind of pressure to get good results.

"Surely we can improve a lot of things. In a sport as complex as football, there's always room for improvement. We're at a good moment and we have to take maximum advantage."

"I see the fans enjoying the team. I see the players really wanting to participate and I see the faces of those who can't participate and they really want to," he continued. "These players are very smart and we know perfectly that we are in the first third [of the season] and the best part is still to come."