Gianfranco Zola believes Diego Tristan and David Di Michele can roll back the years and roll over Liverpool on Saturday.

The West Ham United manager said his experienced strikers, both 33, have the quality to help the Hammers secure a victory that will boost their challenge for a top-seven Premier League finish.

Seventh place would see West Ham qualify for next season's inaugural UEFA Europa League, a target Zola is eager to reach.

With England internationals Dean Ashton and Carlton Cole sidelined by ankle and groin injuries respectively, the manager has been delighted with the contributions made by Tristan and Di Michele in recent weeks.

Former Spain forward Tristan, who was La Liga's top scorer in 2001/02, has stepped up to the plate by scoring vital goals at Aston Villa and Stoke City, and Zola has been pleased with the player's application since he joined the club on a free transfer last autumn.

"Diego Tristan has been producing the performances and the goals that we need right now and that is a bonus.

"The problem with Diego was only the physical conditioning. When he first came here in November he wasn't as good as now physically. Other than that Diego Tristan has got everything. He can be a top striker in Europe, easily. Obviously he has to be supported by very good conditioning, especially in the Premier League.

"You can check and you can see he is a player. He has been a top player for Spain and top scorer in his country for many years. He just lost a little bit of it over the last few years but he's getting it back very, very quickly.

"In the last few games he has been outstanding. The way he played against Chelsea and Stoke City was quite remarkable."

Tristan's current contract runs out at the end of the season, but Zola admitted that the Spaniard's form could see Tristan extend his stay in east London.

"His contract ends at the end of the season and after that we will see. Obviously he's putting himself in a strong position and he's still got three games. I think he's playing for his future but, more than that, he is playing because he is enjoying it. I haven't spoken to him yet but I believe he may want to stay."

While Di Michele has failed to find the net since the 2-0 home win over Stoke on 28 January, Zola insisted that the on-loan Torino man was still playing an important role in the team's bid for European qualification.

"That's something we will consider. Di Michele is another player who has been playing very, very well. Unfortunately he hasn't scored as many goals as he should but his game has been outstanding. For me he has been a key player because he is the one player who makes the team play very well."

A further bonus came with news that Ashton is making good progress in his rehabilitation following a long-term ankle injury. The 25-year-old was due to visit a specialist and Zola is optimistic that he will be fit to join his team-mates in pre-season training in early July.

"Deano is doing very well and is intensifying his training work and so far it's going very well. I believe he is having a meeting with his specialist to discuss his progress but he's looking very well. I believe [he will play a full part in pre-season training]."