Pep Guardiola has said Erling ­Haaland’s body language in the first half of Manchester City’s win over Everton was “not good”, with the manager saying that the No 9 should still hold himself positively when not scoring.

Haaland failed to register before the break on Saturday before proving the champions’ match-winner with strikes on 71 and 85 minutes. These were the 23-year-old’s first goals in a third game back following a foot injury that kept him out for two months.

“These two goals will help him a lot, to clear the mind,” Guardiola said. “His body language in the first half was not good. The second half was much, much better. For him when he scores a goal, his mood is different. After it he makes more movements and everything. He’s better.

Related: Premier League: 10 talking points from the weekend’s action

“He has to learn that if he doesn’t score he has to have the right body language. He has to have this mood where he’s positive and he’s saying: ‘OK it will come, it will come.’”

Haaland, who is expected to start in Tuesday’s Champions League last-16 first leg at Copenhagen, has 21 goals in 25 appearances in all competitions this season. Guardiola has no long-term concerns regarding the Norwegian.

“It looks like I am complaining about Erling but it was in general [I meant]. How many games did Erling play and how many goals? His body language is not a problem. Erling is young, playing in the most difficult position on the pitch surrounded by four or five players with minor space,” the manager said. “In the first half maybe we didn’t have the special delivery players, like Kevin [De Bruyne, who later came on] for example, who can find him.

“Because he is so young, in that moment he has to be positive. When he scored a goal, he reacted but he doesn’t need to score because he helps us for many things. Not just scoring a goal. He’s a huge competitor who wants to score goals. OK, I know that, we know that; so [he can] relax. If we don’t score today or if he doesn’t score in 10 minutes, it’s OK but in the process he has to try to be ‘let’s go’ because the team always wins when they overcome bad moments.”

Haaland has a record 40 goals in 35 Champions League games. “In the Champions League not even [Lionel] Messi or Cristiano [Ronaldo] had these numbers at his age,” said Guardiola.

Copenhagen have not played for two months due to the Danish winter break yet Guardiola still expects a ­difficult night. “There will be moments when we suffer. In these moments will we be sad and depressed or will we react?” he said. “We have to understand that [for] the opponents every player has a mama and a papa so they deserve to play good.”