Pep Guardiola said Erling Haaland's goal-scoring record is reaching the levels of Lionel Messi and Cristiano Ronaldo, but believes the striker is capable of getting even better in the years ahead.

Haaland, 24, scored the opening goal on 18 minutes as City started their quest for a fifth consecutive Premier League title with a 2-0 win at Chelsea, sealed with Mateo Kovacic's 84th-minute strike.

The Norway international marked his 100th league appearance with his 91st goal, and Guardiola claimed that Haaland's summer off -- Norway failed to qualify for Euro 2024 -- has left him feeling sharper ahead of the new campaign.

"He has the numbers for Messi and Cristiano Ronaldo, who controlled the last decade, 15 years, absolutely everything," Guardiola said. "In terms of numbers, it is that level. So, I don't know how he does it, but in 100 games scoring 91 goals is something in Premier League, in this country, is unbelievable.

"I had a feeling that he feels better than last season at this stage. After travel last season, he felt a bit [so-so] or felt he was tired. This season, I think for the Euros unfortunately Norway was not there, there was more rest and yeah, he feels good.

"The goal was magnificent. His contribution in many things. He had two or three chances and always I had the feeling there is a gap to improve as a football player."

City could face a mammoth 75-game season if they reach the final of every competition, including next summer's FIFA Club World Cup in the United States, and Guardiola admitted he could be swayed into giving players individual breaks during the season as first suggested by Real Madrid boss Carlo Ancelotti.

"Maybe, and if Carlo says it, maybe I have to pay attention and I will follow him," Guardiola said. "Maybe in some moments, they play a lot, a lot, go one week at home, don't be in the training session and come back. That's why in preseason, after winning what we won, a lot of games, [they need] to refresh. If you are tired here [in your head], forget about it, you cannot sustain.

"There has to be a desire to be here, to still enjoy to play football, enjoy the training sessions, to be in the locker room together. When this happens, after you can demand everything.

"Without that, they are tired because season after season, games after games, World Cup, Euros, all of them, the body and mindset arrives 'It is enough," Guardiola continued. "When you have that feeling, go home, we play with the academy. We play with other players, it doesn't matter. Otherwise, it is not positive."