Sam Allardyce believes a strong showing from his West Ham side in a goalless draw at Chelsea last season played a part in keeping him in a job.

The Hammers boss, who also learnt on Wednesday that Alex Song will not be traveling to link up with Cameroon for the African Cup of Nations, returns to Stamford Bridge on Boxing Day having transformed his team into top-four contenders.

Chelsea had 39 shots on West Ham's goal in the January draw but lost ground in the title race as they were frustrated by an Allardyce side fighting for their lives at the bottom end of the Barclays Premier League table.

The hard-fought point took West Ham onto 19 points from 23 games and, with 31 from their first 17 fixtures this season, Allardyce admits he may not have been able to implement such a turnaround had his side slipped to a big defeat across London.

"Chelsea can beat you five or six-nil on their ground," he said.

"I think, on the back of our results before we went there it would have made life for the owners even more difficult to get behind me – but that's not water under the bridge, it's water in the sea, water in the Atlantic Ocean it is that far gone.

"We're a completely different unit, team and squad now and we're enjoying our football this year and enjoying our Christmas a lot more than we enjoyed Christmas last year.

"We've got the two hardest games over 48 hours over Christmas – Chelsea away and Arsenal at home in the space of 48 hours is a big demand for us, even though we're on top of our game at the moment. Getting through these two games is going to be a tremendous effort for all the players selected, and hopefully they'll come through for us as they have done for most of this season."

Blues' manager Jose Mourinho famously branded West Ham's football from the '19th century' following the draw.

The Portuguese has since built a relationship with Allardyce after the pair managed the two teams involved in this year's charity Soccer Aid match and Allardyce feels those comments should have been seen as complimentary for his side at the time.

"It was memorable for how well we played," the 60-year-old replied when asked about the fixture and Mourinho's comments.

"I think they (the remarks on West Ham's style) were a compliment by the fact a frustrated manager vented his frustration about the fact that he couldn't break down the team he was playing against.

"That frustration spilled over into his press conference, because he felt he should have beaten us, obviously because of the position that we were in at the time, and the position they were in.

"It's always a compliment for me when a manager has a little pop at you about the way you played or what tactics you might have used, which means tactically you have been very good, you've done your job well and made sure the opposition have found it very difficult to break you down and beat you when all expected us to lose, and we didn't.

"It was part of our recovery at the time, when we'd had such a bad Christmas and New Year. The confidence we gained from such a result was part of us moving forward and getting out of the relegation zone."

The draw may have been seen at the time as a huge step forward for West Ham, but this time around, sitting inside the Champions League places, Allardyce wants even more from their London derby.

"This one is totally different," he added.

"We're fourth in the league this time and we've got better, younger players and hopefully we will go and give a good account of ourselves – and a good account of ourselves is getting a result, not playing well and a loss."

"I think our position speaks for itself that we have got better players and that Chelsea have also got better players than last season – that's why they have gone one step closer to the title, it looks like, than they did last year.

"We have obviously improved tremendously from where we were, but that doesn't make it any easier for us playing Chelsea at Stamford Bridge because of the force that they are, and because of the manager that he is – he is probably the best working club manager in the world at the minute on his track record. I don't think there is any doubt about that."