Mikel Arteta admitted Arsenal were lucky in a 2-1 win over West Ham, but was pleased with his team's belief on Saturday.
After Michail Antonio cancelled out Alexandre Lacazette's opener at Emirates Stadium, Eddie Nketiah came off the bench to score an 85th-minute winner for Arsenal.
West Ham had 14 attempts at goal to Arsenal's seven, although Bernd Leno was only forced into two saves.
Arteta said Arsenal, who have won their opening two games, were fortunate in the London derby.
"We were a little bit lucky in certain moments for sure," the Arsenal manager told a news conference.
"But as well, we find a way to win it and it's the mentality I want that the team always believes that we can do it up until the last moment. Even if we have difficult games where we suffer, we make it difficult for ourselves in certain periods, but in the end it's three points.
"This is why we are here. As well, take some big notes because there are a lot of things to improve."
Arsenal are one of three teams to have grabbed six points from their opening two games in the Premier League so far. However, Arteta believes they are still some way off being genuine title contenders.
"I think we are still very far away from where we want to be," he said.
"I think if you ask any manager in the Premier League if they are happy with everything [that] is going [on] with their team, it probably is no.
"We had a super-mini pre-season and we're still adapting some things. Some players are still not 100 per cent fit either but it's great to start winning, to have six points already and find ways to win."
Arsenal face Leicester City in the EFL Cup on Wednesday with their next Premier League game to come against reigning champions Liverpool on September 28.
After scoring the winner against West Ham, Nketiah addressed a recent bust-up with Dani Ceballos, who provided the assist for his goal.
"We had a bit of a coming together. The reaction was there. We made up an got on with it. It was nice for him to make the assist. It's all love now," Nketiah told Sky Sports post-match.
"It was a great pass across, good vision. I tried to stay onside. It was an easy finish from there.
"I want to keep improving as a player. It's a great feeling to come on and score. West Ham made it very difficult. They came out very strongly in the second half."