Arsenal manager Mikel Arteta has claimed Chelsea have the "strongest squad in the Premier League" ahead of the London clubs' Boxing Day meeting, which kicks off a week that the Gunners boss said will define their season.
Arsenal beat Chelsea in August's FA Cup final at Wembley, but the two clubs have endured vastly contrasting fortunes since then.
While the Blues have spent more than £220 million in the summer transfer market and are placed just outside the Champions League places after 14 games, Arteta's men are just four points above the relegation zone having lost eight times, including four of their last five league matches.
Arsenal are set to be without their biggest summer signing, Thomas Partey, and club captain Pierre-Emerick Aubameyang is a doubt with a calf problem. Chelsea are missing Hakim Ziyech due to a hamstring injury and Ben Chilwell is a doubt with an ankle knock but their other four acquisitions -- Timo Werner, Kai Havertz, Thiago Silva, Edouard Mendy -- are fit.
"Obviously Chelsea always have a great squad of great players," Arteta said. "The team that we faced a few months ago was a top one.
"In this moment, you're probably talking about the strongest squad in the Premier League. They're doing a really good job, Frank [Lampard] is doing a really good job. He's got a team full of belief and confidence, and even though they had some defeats, they got back to winning on Monday [beating West Ham 3-0] and it's a team that is going to be fighting for the top spot in the league for sure.
"I wouldn't like to compare [them with Arsenal]. What they did seems to be working fine and at the moment we are not there."
Arteta is under mounting pressure after Arsenal's worst start to a season since 1974. The 38-year-old retains the support of senior figures at the club and belief in his long-term vision remains, but results must improve with trips to relegation-threatened Brighton and West Brom either side of New Year's Day.
"The next seven to eight days are going to be crucial to see where we're going to be heading to in the Premier League," Arteta said. "The best medicine when you are in this situation is to win a football match. Every defeat is another hurting moment, another moment of disappointment, another moment you have to lift yourself up and that's what we've got to do.
"I think the medicine for all of us would be to come here against Chelsea, beat them and then move from there. It's exactly what we all need."