The Gunners were knocked off the top of the table after Liverpool's win over Cardiff on Saturday lunchtime, and were soon pushed down into third place when Manchester City won 4-2 at Fulham.
Should Chelsea win at the Emirates Stadium tonight, the Gunners - who once held a five-point lead - will be fourth at Christmas.
Asked if people were right to question Arsenal, Wenger said: "Yes - we haven't won the league for a long time, so that is why they question us.
"It is not (about nine seasons) without winning a trophy, it is without winning the Premier League.
"If you win the League Cup, it does not change anything.
"It is the Premier League that is the most important thing, and we haven't won it for nine years.
"Of course, it does not strengthen your belief, because if you win it every year, you go in there and (say) 'it is just ours', so it makes the challenge (now) more interesting."
Wenger continued: "At the moment everybody still questions us, even more after our defeat at (Manchester) City.
"But I see the game at City the other way round, that we can have even more belief after the game at City."
Wenger maintains his men can rise to the challenges of character they will face again in the first of their hectic festive fixtures.
"It adds pressure, but you cannot play in the Premier League without pressure," the Gunners boss said.
"There are periods where the pressure is a bit bigger and periods where it is smaller.
"You have to live with that and resist that kind of stress."
Wenger added: "People are only keeping in their mind the big matches that we lose, but we have won some big games.
"What is at stake is if you want to win the Premier League, you want to win the big games at home. It is as simple as that."
One player who is certainly due a big performance is Mesut Ozil.
The German playmaker has only shown glimpses of his class since a £43million club-record move from Real Madrid.
Wenger, though, has every confidence Ozil will come good on a regular basis soon enough.
"I believe that he has a personality. He works quite hard and is adapting to the physical challenges of the Premier League at the moment," said Wenger.
"Ozil looks to me like (Robert) Pires. It took a while for Pires to adapt to the physical side of the game.
"Once he had adapted he was absolutely amazing and Ozil is a similar type of player."
Source : PA
Source: PA