Pep Guardiola underlined the importance of calmness after his Manchester City side beat West Ham in a match which featured heavy use of VAR.
"You have to be mentally strong when VAR is not on your side," said the Spaniard after the match.
"You think at 0-3 the game is almost over but at 0-2, the game is completely different. You have to be calm and be strong, it is going to change the dynamic not just for the team but for the spectators."
Gabriel Jesus and Raheem Sterling had put City 2-0 up before the Brazilian became the first player to have a goal disallowed by VAR in the Premier League after Sterling was adjudged to have been offside as he played the ball through.
Manchester City's Brazilian striker Gabriel Jesus celebrates with team-mates after scoring the opening goal during the English Premier League football match between West Ham United and Manchester City at The London Stadium
Manchester City's Brazilian striker Gabriel Jesus celebrates with team-mates after scoring the opening goal during the English Premier League football match between West Ham United and Manchester City at The London StadiumGetty Images
VAR, making its debut this season, was used again to review and eventually validate Sterling's second, when he collected a lofted ball into the box and lobbed West Ham keeper Lukasz Fabianski.
In the 84th minute, City were awarded a penalty for Issa Diop's foul on Riyad Mahrez. Substitute Aguero's soft penalty was saved - but VAR ruled that Declan Rice was encroaching into the box and referee Mike Dean ordered a re-take - which the Argentine slotted home.
Guardiola was pleased with his team's second-half display but had some critical words for their performance in the opening 45 minutes.
"It was difficult away from home, 12.30 kick-off, hot. The first half was not good. We didn't control second balls and lost a lot of balls," he said.
"It was important to get three points, a clean sheet. At 2-0, they have a chance. Overall for the first game it is an incredible result.
"The second half was much better. More calm, but still we have many things to improve."