Arsenal failed to make up ground on Premier League leaders Liverpool after 1-0 defeat to West Ham United at the Emirates Stadium.
Gunners coach Mikel Arteta made two changes from the win over Leciester City, as match-winner Mikel Merino replaced Raheem Sterling to lead the attack while Myles Lewis-Skelly made way for Myles Lewis-Skelly at left-back.
The opening exchanges of the first half proved to be cagey affair, although the home side did enjoy more of the possession without creating much going forward.
West Ham, meanwhile, defended quite deep in their own half as their central defenders were not entirely bothered by Merino upfront, although they did not offer any attacking outlet for the early parts.
The visitors did get the opening goal on the counter-attack before the break when Aaron Wan-Bissaka got the byline before picking out captain Jarrod Bowen to head home.
Arteta looked to switching things up in the first half by throwing on Oleksandr Zinchenko for former West Ham midfielder Declan Rice while Lewis-Skelly entered the pitch in place of Calafiori at left-back.
Lewis-Skelley did not make the desired impact after the teenager was sent off in the 73rd minute for a foul on Mohammed Kudus, who was about to race clear on goal before being pulled down.
There would be no late show from the Gunners, as West Ham defended with 11 players behind the ball to secure the victory.