Carlo Ancelotti could be without Didier Drogba against Portsmouth tomorrow, but welcomes back Alex into his starting line-up.

The defender has been out for three weeks with a thigh problem, but after returning to full training last week, is able to make a first start of the month, in place of Ricardo Carvalho who Ancelotti expects to return against West Ham at the weekend.

The Italian is hoping that he will not be forced into any further changes, but could see Drogba ruled out after he took a knock on his back in training.

'We had a problem this morning in training with Drogba, he took a knock on his back and I don't know if he can play tomorrow, but Alex and Kalou return. I don't want to change a lot of players for tomorrow,' Ancelotti said, adding on Drogba: 'We have to control his condition and will take a decision. I think that he can play.'

This rare midweek league game offers an opportunity to put things right immediately after the disappointment of Saturday's 3-3 home draw against Everton, and Ancelotti was keen to explain the work that has gone in on the training ground over the past days.

'We trained on set-pieces because we conceded in this season some goals in this situation and we have to improve, we want to improve, because we can do better. We had the same problem after the game against Aston Villa two months ago and after that game we did very well, and now we have to return,' he said.

'We conceded a lot on the set plays, but only two in open play, which means we have a very consistent defence, we have fantastic defenders. We have to improve their communication and attention, and avoid silly fouls near to the box. We can start to do this tomorrow, we keep 11 players in the box and they have to have a good communication.'

The 50-year-old also pointed out that it is not only Chelsea who have conceded set-piece goals this season.

'Only two teams have conceded only two goals on set pieces, other teams seven, eight, nine, 10. Arsenal conceded 10, Liverpool conceded 10. Every team has this problem.'

Ancelotti also reaffirmed his belief in Petr Cech, who conceded three for the first time this season at the weekend, in the process rubbishing reports linking us with West Ham's Robert Green.

'Every one of us thinks we have the best goalkeeper in the world, at the same level of Buffon or Casillas,' he said. Everyone thinks this. He is a very professional player, he maintains a good control, always.'

In spite of the overexposure on the issue, we remain four games without victory, and Ancelotti is desperate to put that right against the Premier League's bottom club.

'It's very important to win. When it's not possible we have to look at what happened. We didn't win the last four games but I think the team is in a good moment, I don't see big problems about this. If there is a problem we can find a solution immediately. I feel the team is doing good football but we have to put more concentration and focus on the set-pieces.

'We were unhappy after the [Everton] game because we drew for the first time in Stamford Bridge, conceded a goal after 10 games, and maybe Manchester United could arrive at the top, but after the Manchester United game we were more happy. I watched with a glass of red wine and [was] a little bit scared, but Aston Villa is a very dangerous team, they won against Chelsea, against Manchester Untied. I think Martin O' Neill is doing a fantastic job with this team. Maybe we have to pay attention because nobody spoke about Asont Villa in the top four.'

Wednesday's game also represents a first return to the Bridge for new Portsmouth manager Avram Grant, since he departed in May 2008.

'I don't know him, I saw him take Chelsea in the Final of the Champions League and for this he did a very good job in that season,' Ancelotti said. 'From his arrival in Portsmouth he is doing a good job, Portsmouth did in three games four points and we have to play a strong team tomorrow because they will do a good job to try to win.'

Some tickets still remain for the Portsmouth, available at the Box Office only.