Arsene Wenger has blamed the fatigue provoked by a congested run of away fixtures for his Arsenal team's defeat at Everton.
The Gunners suffered their first league reverse since the opening day of the season when they surrendered the lead afforded them by Alexis Sanchez's first-half opener at Goodison Park to lose 2-1 on Tuesday.
It means Arsenal could fall six points behind leaders Chelsea should Antonio Conte's in-form men win at Sunderland on Wednesday, and may even find themselves pushed down to third if Liverpool win by three goals at Middlesbrough.
Wenger, 67, told SFR Sport his squad were paying for having last weekend's 3-1 win against Stoke City as their only home game in five competitive outings.
"You have to accept in football that you can win and lose. The most important thing remains the next game," said Wenger, whose team travel to Manchester City next. "I have to pick up the troops, focus on Sunday. But we have played at West Ham, Basel, here and then Manchester City. It means we will have played one game in five at home, and that takes a lot of energy."
After a positive start, and Sanchez's goal, Arsenal were outfought by Everton. Seamus Coleman equalised just before the break and Ashley Williams, who had inadvertently deflected Sanchez's free kick past his own goalkeeper, headed home four minutes from time to secure a 2-1 home win.
"The first 20 minutes it was rather one-way traffic, but they made the game much more aggressive after that and it troubled us," Wenger said. "In the second half, we retook control of the game, but we never found our real fluidity going forward, there were a number of challenges that were right on the limit, you have to deal with that. In the end, we conceded two goals by defenders from two crosses.
"We had been warned before the game that we had to avoid that, and we paid for it. We deserved to take a point, but that's not the way it turned out. We have to accept it."
He added: "Ozil had a great chance in the second half, we could at least have equalised. It's the cruel rule of sport: if you don't take your chances ... I think we blocked quite a lot of their crosses, but we were taken a little by surprise by the two centres [for the goals]."
Speaking after the loss, Wenger said Everton's physical approach managed to disturb the Gunners as they fell to their first away loss of the season.