Manchester City striker Sergio Aguero could equal the club's all-time goalscoring record in Tuesday's Champions League match against Shakhtar Donetsk and his manager Pep Guardiola believes he has become one of the best strikers in the world.

Aguero's goal in the 5-0 win over Crystal Palace on Saturday took him to within one goal of equalling Eric Brook’s record for City with his 176th goal for the club in all competitions.

"I hope as soon as possible he can achieve that record so at least we can not talk about that. I am pretty sure that in the next game it is going to happen," Guardiola told reporters on Monday.

"Last game again he scored a goal and had two or three chances more so that is essential for a striker that you have (chances).

"It helps a lot that Ras (Sterling) got two more goals (against Palace). We are able to score more goals with more people. The opponents are more focused on other guys then he is more free to score more goals. Sergio is in no doubt one of the best strikers in the world," he said.

Guardiola says Argentine Aguero has kept his ability to be deadly in the penalty area while becoming more a part of the team's overall play.

"Maybe now we play more with him. We are looking not just in the finishing. Before maybe Sergio just scores a goal," the Spaniard added.

"Now in the process. ...we know always he is there. His first metres is so quick and he is so powerful in the legs and I am so happy he is doing that."

City, who thrashed Feyenoord 4-0 in their opening group game, will be without captain and central defender Vincent Kompany who is sidelined with a calf injury and Ilkay Gundogan who is out with a knee problem.

French left-back Benjamin Mendy faces a fitness test on his knee injury.

Guardiola said it was vital his team did not under-estimate their Ukrainian opponents who got their Group F campaign off to a good start by beating Napoli 2-1.

The City manager said he had always had difficult games against Shakhtar during his time at Barcelona.

"Always was so tough for me. For Barcelona, we have good results but it was so tough.

"They beat one of the best teams in Napoli. Napoli are one of the three or four or five best teams, they are leading the Italian league and Shakhtar beat them.

"That group is tricky. The players today are going to see how good they (Shakhtar) are and hopefully I can convince them to take them seriously. At this level you cannot concede a lot of minutes not playing well."