Declan Rice lambasted Arsenal for their "naivety" this season following their 2-0 loss to Bournemouth in which they were reduced to 10-men for the third time this season.
The game at Vitaly Stadium turned on its head in the 30th minute when William Saliba was sent off for a foul on Evanilson near the halfway line after an awry pass from Leandro Trossard. The France international was initially shown a yellow card before a VAR check saw it upgraded to a red.
Bolstered by their man-advantage, Bournemouth began playing with greater attacking endeavour and found the breakthrough in the 70th minute through a well-worked Ryan Christie goal before a Justin Kluivert penalty condemned Arsenal to their first loss of the season.
"We've kicked ourselves in the foot three times in eight games and we got away with it at home to Brighton and away at Manchester City. Bournemouth kept probing and made it 2-0," Rice told Sky Sports after the game.
"I'm proud of the players for fighting, even with 10 men, but the naivety, we need to stop making mistakes because you want 11 players for 90 minutes and that's what wins you football matches.
"With 10 men we showed a lot of character and personality to stay in the game. The big chance was [Gabriel] Martinelli's and the keeper read it and made a great save and one minute later, normally a routine we are so strong at, has done us.
"We can't make silly mistakes. You need all your best players on the pitch at all times. The belief is so high and we will stick together. This is football, whatever happens the most important thing is that you stick together and stay in the right direction."
Arsenal boss Mikel Arteta, too, was left ruing the Martinelli chance, where the Brazil international failed to slot past Kepa Arrizabalaga from close range.
"We had the big chance and the moment in the game to score and have a different result and then we conceded a goal. We try to stick to the rules. The three [red cards] have been different ones and three very different outcomes," Arteta said.
"The team tried, the effort with 10 men was fantastic but today it was not enough to win the game. It took us a while to understand what we had do in the first 15 minutes to start with, then we grabbed the game but after 30 minutes the game changed."