PRE RACE favourite Dionisio Ceron of Mexico is seeking an unprecedented hat trick of wins in the London Marathon tomorrow.

However, he will be under pressure from one of the most competitive fields in the 16 year history of the race.

Ceron finished 24 seconds ahead of Ethiopia's Abebe Mekkonen in the 1994 marathon and last year out ran Australian Steve Moneghetti to achieve his personal best time of two hours eight minutes 30 seconds.

But among the record field of 27,900, Ceron will come up against some of the world's top runners who are competing for places at the Olympic Games in Atlanta.

Only eight runners have run under two hours eight minutes in 88 years and Belgian Vincent Rousseau has done it twice.

Rousseau, who is the second fastest European to run the distance, believes a world record is still possible on Sunday.

The Belgian is looking to break the eight year mark of two hours six minutes 50 seconds belonging to Ethiopia's Belayneh Dinsamo.

It's difficult to say how fast we will run because there are a lot of things to consider, but a very fast time is possible," said Rousseau. A £100,000 prize is on offer for a world best, with £25,000 for anyone beating the course record of 2:8.16 set by Welshman Steve Jones in 1985.

Rousseau, who will not compete in Atlanta because it will be too hot and humid, will be happy with the weather forecast for Sunday which is expected to around 17 degrees Celsius at midday.

Rousseau is the joint favourite for Sunday's race with Ceron but the pair are not likely to have things all their own way.

Mexico's German Silva, who has won the New York marathon for the last two years, returns to London with the aim of improving on his third place in 1994.

In the women's event, double winner Norwegian Grete Waitz believes Britain's Liz McColgan can put her injury dogged career back on track and beat defending champion Malgorzata Sobanska.

Waitz, successful in 1983 and 1986, agreed to coach the former world 10,000 metre champion last year after suggesting at a chance meeting in Florida that her training was going in the wrong direction.

The Norwegian, nine time New York Marathon winner, said: "I saw some of the mistakes I made in my career. When I see now what she is doing in training, there is no reason, why Liz cannot run as fast as I did and on the right day even faster.

A second rival to the Scot has pulled out through injury. Finland's Ritva Lemettinen, third last year, has joined 1990 winner Wanda Panfil, of Poland, on the sidelines.

. Chinese running coach Ma Junren believes his hospitalisation will have a negative impact on his team's prospects at the Atlanta Olympic Games.