Chelsea striker Salomon Kalou has given coach Carlo Ancelotti a massive selection headache ahead of their Champions League return clash with Atletico Madrid.

Chelsea crushed the Spanish side 4-0 at Stamford Bridge a fortnight ago with Ivory Coast international Kalou scoring twice in the rout.

Kalou's Ivory Coast team-mate, Didier Drogba, was suspended for their opening three Champions League games, but he is available for selection when the Blues face Madrid on Tuesday night.

Kalou has struck up a fine partnership with Nicolas Anelka in Drogba's European absence as Chelsea have soared to the top of Group D with 1-0 victories over Porto and Apoel Nicosia prior to their drubbing of Atletico.

Ancelotti will now have to decide whether to recall Drogba against Madrid or stick with Kalou and Anelka in attack.

"It is good to be back on the pitch and scoring goals," said Kalou. "As a striker it gives me a lot of confidence.

"Against Madrid we knew it was important to run behind their defence because they always try to play the offside line and so when Anelka dropped deep, it gave me the time and space to arrive in front of goal every time.

"So it was a good combination between me and Anelka and it paid off because I scored two and I could have scored more.

"But in the end it is good enough that I put two in the net. At the start of the game I played behind the striker on the line-up but the thing is Anelka and I can always switch positions.

"It doesn't matter who is in front or who drops back, there is always a good combination. I suppose it happens because he is the kind of player who likes to go to the ball and I like to run beyond the defence sometimes so it gives us a choice of who plays behind."

Kalou is relishing his new role as a central striker after spending much of his time since joining the Blues out on the wing under previous managers who preferred to play with a 4-3-3 formation.

Ancelotti's 'diamond' system is suiting Kalou's game and the Ivory Coast star is more than happy with the upturn in his fortunes.

"I was playing in the middle for a while at Feyenoord but when I came to Chelsea we had the set-up with the wingers," said Kalou.

"I can play on the wing but now I am happy to be back in my favourite position because I can show the best of my game."

Victory over Madrid on Tuesday will almost certainly guarantee Chelsea a place in the knockout stage of the competition. They have yet to concede in Europe and Kalou is full of praise for the tactics and systems of former AC Milan coach Ancelotti.

"He brings the experience he got at Milan here and has set us up very well - everyone feels included in the team and that's very important because you know you will get an opportunity to play," added Kalou.

"When a player knows he will have an opportunity some time then he will give his best all the time."