West Ham forward Marko Arnautovic could be back in training next week.

The five-goal Austrian suffered a hamstring injury against Cardiff on December 4 and was expected to be sidelined until well into the new year.

But boss Manuel Pellegrini revealed Arnautovic is ahead of schedule, meaning he could even be involved in the squad against Southampton on December 27 and Burnley three days later.

"We will need to see his last examination, but I think that next week he will start working with the team," said Pellegrini.

The outlook is less optimistic for injury-plagued Jack Wilshere, who has played just five minutes since September due to two separate ankle problems.

"We don't know (when he will be back), we will need to wait for the medical assessment but for this moment, we cannot be sure," said Pellegrini.

The Chilean boss still expects to complete the signing of Samir Nasri on January 1.

The former Manchester City midfielder, a handy replacement for Wilshere if he is ruled out long term, is building up his fitness following an 18-month ban.

Press Association Sport also understands West Ham are exploring the prospect of signing ex-Cardiff midfielder Gary Medel from Besiktas, although Pellegrini remained tight-lipped.

"Those names may be one of 25 names that have been said recently, and it is always the same answer, I do not talk about rumours, I am happy with the squad," he said.

"I know that we need to replace players that probably will not play much more this season like (Andriy) Yarmolenko, (Carlos) Sanchez, (Manuel) Lanzini, so we are calm, we will decide not now what we are going to do but we will decide."

West Ham host Watford on Saturday looking to make it five Premier League wins on the trot for the first time since 2006.

"The most important thing is to be in the top six at the end of the season," said Pellegrini.

"There are still 21 games to go. We are in a good moment now so we must try to take it game by game and add points."