Emmanuel Eboue insists Arsenal have recovered their winning mentality ahead of their trip to Stamford Bridge on Sunday.
After enjoying a five-match unbeaten streak in the Premier League, the Gunners were brought back down to earth last weekend when they suffered a 3-2 defeat at the hands of promoted West Brom.
But Ivory Coast defender Eboue feels Tuesday's 3-1 UEFA Champions League triumph at Partizan Belgrade has put his side back on course as they prepare to visit Chelsea at the weekend.
"We started very well in the league, but last Saturday's defeat was a big blow," Eboue told skysports.com.
"But our spirit is strong, we came away from home in Europe and won 3-1.
"Our winning mentality is back, and we really need that to meet Chelsea on Sunday."
Table-toppers Chelsea also endured the first defeat of their league campaign last weekend as they were seen off 1-0 at Manchester City.
But, like Arsenal, the Blues went some way to compensating for their weekend loss with success in Europe on Tuesday night, securing a comfortable 2-0 victory over French giants Marseille.
And 27-year-old Eboue knows the Gunners will have to be on top form to stand a chance of overthrowing their local rivals at Stamford Bridge on Sunday.
"They are a big and powerful team and are in good form, despite losing last weekend," he added.
"If you are not strong and ready against them, they will overpower and destroy you.
"So we will be ready against them, we are very confident about that."