"That was missing from the last few games".
The Gunners also handed Conte the most chastening defeat of his reign earlier that season with a 3-0 victory in the league, as well as defeating Chelsea in the Community Shield at the start of this term.
The Gunners' performance improved significantly on Thursday night with the introduction of Sead Kolasinac as they reverted to four across the back.
Arsenal have kept only one Premier League clean sheet in their last 18 games at Stamford Bridge. Veteran boss Wenger did opt to include wantaway striker Alexis Sanchez in the starting lineup but his selections couldn't do anything to stop Jurgen Klop's deadly charges as they mercilessly tore apart the helpless Arsenal in a resounding 4-0 humbling.
Arsenal, meanwhile, head into the game after victories at home against Bournemouth and Cologne.
On current form, it's hard to argue with any of Merson's selections.
The defeat prompted stern criticism from pundits and former Gunners.
What do you make of Merson's selections?
"It is important, of course it's very important", he said about getting a result at a rival.
Danny Welbeck has three goals in four Premier League appearances this season, after netting just two in 16 games last term.
Arenal are looking for their first win at Stamford Bridge since 2011.
The Group H game, which Arsenal won 3-1, was due to kick-off at 1905 GMT but European soccer's governing body UEFA, which organises the competition, said 45 minutes before the scheduled start it would be put back "in the interests of crowd safety".
After Arsenal's 3-1 win, Arsene Wenger said that he had expected the match to be cancelled, before then admitting that he felt it was the right decision to let the game go ahead as planned as there was "no aggravation".
"I hope to finish the game with 11 players - in the last two games, the FA Cup final and the Community Shield, we finished with 10 men - then during the game the best team will win", Conte told reporters on Friday.
That day at Arsenal has come to be recognised as modern Chelsea's D-Day, the point at which the new manager abruptly completed his detached assessment of a squad that had in the previous 18 months gone from league winners to mid-table and set about reorganising.
Chelsea lost an eventful FA Cup final to Arsenal in May.