Hansi Flick has challenged Leroy Sane to improve his game if he is to hold down a starting spot as the Bayern Munich coach prepares to welcome back Serge Gnabry.

Germany winger Gnabry missed the 4-0 Champions League win over Atletico Madrid and the 5-0 Bundesliga thumping of Eintracht Frankfurt after testing positive for coronavirus.

However, the Munich health department declared on Sunday that the original test was a "false positive" and he is now in line to start Tuesday's trip to Lokomotiv Moscow.

"He is certainly an option for the starting line-up, as he always is when available," Flick said at Monday's pre-match news conference. 

"He did what he could while isolating at home. He's happy to be back and we're also happy that he's back."

Gnabry scored 12 goals and provided 10 assists in the Bundesliga last season and began this season with a hat-trick in the 8-0 thrashing of Schalke.

Sane has made a positive start to life at Bayern since belatedly making his debut last month, meanwhile, scoring and assisting a combined four goals in three appearances.

That is behind just Robert Lewandowski (13 goals and assists) and Thomas Muller (seven), while his eight chances created is only bettered by Muller (18), Joshua Kimmich (10) and Gnabry (nine).

However, Sane faces a battle holding down a spot in Flick's favoured XI, although the German coach can see the ex-Manchester City attacker offering more in the long term.

"There is a lot of room for improvement," he said. "But he scored a good goal against Frankfurt with a type of goal that helps set him apart.

"We now have another option with Serge back. We have adjusted to each opponent and, regardless of who has played, the players have always been focused and played well."

Gnabry's return coincides with the loss of versatile wing-back Alphonso Davies, who is facing up to two months out after damaging his ankle ligaments in the Eintracht match.

"Losing players is part of competitive sport," Flick said. "You have to deal with stuff like this from time to time. 

"It is not a serious injury but he will still miss between six and eight weeks. He will come back stronger, I'm sure of that. It is our hope that he can pick up where he left off."

Bayern have won all nine of their Champions League games under Flick, netting 34 goals in the process, and are strong favourites heading into their clash with Lokomotiv.

But Flick is wary of writing off the Russian side, who have lost six of their past seven home matches in Europe but held Salzburg 2-2 away in their opening Group A fixture.

"They are one of the most consistent teams in the Russian league," he said. "They have a lot of players on the outside who are very good. 

"I liked some of them very much in the analysis, so we have to be careful. They are a team that knows how to act defensively - 2-2 against Salzburg is a good result."