Arsenal midfielder Denilson knows the Gunners will have to be at their best when they tackle league leaders Chelsea on Sunday, live on Sky Sports 1 and HD1.
Arsene Wenger hit out at his side after their 1-0 defeat by Sunderland at the Stadium of Light last weekend, a result which leaves them eight points adrift of the Blues, albeit with a game in hand.
The North London side bounced back from that disappointment with a 2-0 success against Standard Liege on Tuesday which secured their place in the last 16 of the UEFA Champions League.
Denilson marked his return from a two-month spell on the sidelines with a back injury with a spectacular strike against the Belgians and has immediately turned his attentions to the upcoming showdown with in-form Chelsea.
"I am very happy at the moment. Not only me but also all the group is very happy," he told the club's official website.
"On Sunday we have a hard game against Chelsea, a big team, so every game we have to focus."
He added: "Two months out was very difficult but I am back now so I have to play well in all the matches."
Team-mate Mikael Silvestre has echoed Wenger's belief that Arsenal were below the required standard on Wearside, but was happy with how they responded in Europe.
"I think at Sunderland we lacked a little bit of commitment," the French defender admitted.
"You drop one per cent or two per cent and that's it, you get punished. Against Standard we wanted to rectify this and make sure we got the victory."
Silvestre insists Arsenal put a marker down by getting out of their group with a match to spare.
"We have seen Liverpool go out, Barcelona are struggling," he said. "I think our group was well-balanced and we made a good campaign so we are proud of that.
"It was easy to control the game in the second half as we were 2-0 up. After the disappointment of this weekend it was good preparation for Chelsea too.
"The Sunderland defeat tells us that we can't rest and we have to keep going. We must treat every game the same no matter if it's after an international break or in December when you have a game a week every week. The application has to be the same and so must be the determination."