William Saliba played every minute of Arsenal's Premier League campaign last season, and the French centre-back's absence will leave Mikel Arteta with a difficult task in setting up his defence against Liverpool. Saliba had earlier been sent off against Bournemouth.
Arteta has decided to partner Ben White with Gabriel at centre-back, while midfielder Thomas Partey will play at right-back, while Jurrien Timber has recovered from a muscle injury to play at left-back.
This is the sixth defensive quartet Arteta has used in nine Premier League games this season, and they looked good in the first 45 minutes against Liverpool but the problems worsened in the second half.
Gabriel was forced off early in the second half and returned to the bench to watch the rest of the game with his left leg in a sling. The last Premier League game in which neither Gabriel nor Saliba were on the pitch was the final four minutes of Arsenal's 4-1 win over Crystal Palace in March 2023.
Jakub Kiwior was introduced, but Liverpool pressed on in search of an equaliser. Timber - who started his first game in 26 days - was lacklustre and Arteta was forced to bring on teenager Myles Lewis-Skelly. Mohamed Salah's equaliser came from the same flank.
Saliba will return from suspension, but Arsenal's defence - which has usually been stable and reliable in recent seasons - is now being tested to the limit.
Arsenal are rightly hailed as one of the best teams in Europe at set-pieces at the moment, but for the second week running they failed to defend corners.
After Bournemouth broke the deadlock against the Gunners with a smooth combination, Liverpool did the same. From Trent Alexander-Arnold's cross, the ball went over Luis Diaz's head and then went back for Van Dijk to finish close to the goal, leaving David Raya unable to react. The common point in these two goals conceded by Arsenal was that Kai Havertz failed to compete in the air.
Only Wolves and Southampton have conceded more goals from set pieces than the Gunners in the Premier League this season.
Of course, in attack, set pieces remain Arsenal's most potent weapon. Declan Rice's superb pass in the 43rd minute found Mikel Merino, who powered home a powerful header to give Arsenal a 2-1 lead.
It was the 27th goal Arsenal have scored from dead-ball situations since the start of last season - a league record.
"We dominated the first half, played sharp, effective, determined and should have created a bigger gap. We didn't allow Liverpool to create many chances, and basically gave them two goals. That's disappointing," Arteta said after the match.
