Chelsea were beaten 1-0 away from home by Croatian champions Dinamo Zagreb.
The Blues are currently bottom of the Champions League Group E, and it has been a tough start to the season for Thomas Tuchel’s side.
In what seemed a pretty okay situation with Kalidou Koulibaly and Wesley Fofana at the back against one striker, poor positioning and decision making cost Chelsea to concede an early goal.
Just after 13 minutes of play, Mislav Orsic broke clear of Wesley Fofana to score the only goal of the match.
Orsic surprisingly beat Fofana for pace, before dinking the ball past a hapless Kepa Arrizabalaga.
Mason Mount blamed the defensive mistake as the reason for the defeat.
According to Mount, the team lost concentration and then conceded an easy goal.
The 23-year-old said: “We had opportunities in the first 20 minutes. We were creating, we had a lot of domination with the ball, camped in their half.
“It was going to be difficult to break them down at first but if we’d kept going I feel that the goal would have come but there was a lack of concentration.
“It was too easy when we gave the goal away, we left ourselves open and they made it 1-0. In any game we play it’s very difficult at the level we’re playing at to get back into a game when you’re 1-0 down, especially in the Champions League.
“We didn’t take our chances, didn’t have enough clear-cut chances and in any game you play, especially in the Champions League, you’re not going to get loads of clear-cut chances.
“So you need to take them and the half chances that come around, and obviously stay concentrated at the back because once you switch off for 10 to five seconds they’re on the counter-attack and they score.
“The way we started the game we should have killed it off at the beginning. If we take our chances, score some goals, then the game’s done. We let them feel that they were still in the game and once they got their goal it’s very difficult to get back into it.
“So we need to look at ourselves and our underperformance and come back stronger, because it’s really not good enough. But we’re a team that bounces back and we’re strong. Obviously this is a moment in time when we all need to get together and really look at where we can improve.”