Sergio Aguero and Vincent Kompany
Aguero and Kompany are yet to resume training as City sweat over their fitness Getty Images

Manchester City are without top scorer Sergio Aguero and captain Vincent Kompany for the Champions League visit of Borussia Monchengladbach, with Manuel Pellegrini uncertain when either player will return. Aguero has missed his side's last two games with a heel problem while Kompany has not played since November with a calf injury and the pair are doubtful for the upcoming festive period, which includes a trip to fellow Premier League title contenders Arsenal.

The duo are among six players out of action for City, with Martin Demichelis, Samir Nasri, Pablo Zabaleta and Fernando all nursing problems. Yaya Toure, who missed the 2-0 loss at Stoke City, is also doubtful for the European clash. But the greatest concern surrounds Aguero and Kompany, who are not yet ready to return to training, according to Pellegrini.

"[Aguero] cannot work," said the Chilean boss, according to Sky Sports, whose side face Swansea City and Arsenal before Christmas. "He needs time to recover from the problem, but it is not a serious injury, it is a pain injury. We hope [he can resume training], but we must see how he improves. If he can run, then he will kick a ball, but if he cannot it is very difficult for him to do.

"Vincent is improving. He is doing some tests on his calf and seeing what is the best way forward. We will see in the coming days when he will be able to return."

City travel to Arsenal on 21 November in a potentially pivotal game in the race for the title. Both sides are separated by just one point after 15 games and victory could see either side top the table in time for Christmas. Though Aguero and Kompany have not yet been ruled out of the game, time is running out for the pair to prove their fitness for the it, particularly with neither having resumed training.

Before attention can return to domestic matters in the Premier League, where City take on Arsenal and leaders Leicester City among other amid a hectic schedule, the club must first round off their European group campaign. Already assured of a place in the knockout phase, City can progress as group winners for the first time and avoid the continent's big-name sides if they beat Monchengladbach and Europa League-chasing Sevilla overcome Juventus.

"The defeat to Stoke is gone for us," Pellegrini insisted, according to the club's official website. "We've analysed it already. It's important for the team to at least do their task and we'll see what Juventus do against Sevilla. It's important for the team to finish at the top of the group – our target is just to win our game – we can do nothing about what happens in the other game."