DERBY favourites Deerfield and Charming Talker worked solidly without really impressing on the grass at Sha Tin yesterday in readiness for Saturday's big event, the Hongkong Classic Trial. Alex Wong Yu-on's Deerfield has been off the track due to the flu virus which closed down racing late last year and will almost certainly need his reappearance. That was the enduring impression after he went through a testing 1,200-metre hit-out on the sandmesh yesterday when he went to the line without the sparkle he showed when in peak condition last season. But the good news for his supporters, who still justifiably see him as the likely Derby winner, is that he is undoubtedly on the way back. He will improve for yesterday's gallop and he will progress again for the outing at the weekend. Deerfield's jockey Brent Thomson confirmed the impression from the stand. ''It was good work without being spectacular,'' he said. ''The horse is really well in himself, very happy and relaxed and he enjoyed his work. But he has been off for quite some time and the gallop gave me the impression that, whatever he does at the weekend, he will improve considerably for the run. ''I'm not saying he can't win because he's such a good horse that he could win on his class alone. ''I'm just saying that he is not at his peak yet and why should he be? Alex has done a great job bringing him along slowly from the virus and the aim is to have him spot on for Derby day on March 7 - not for Saturday.'' Patrick Biancone echoed Thomson's sentiments when discussing Charming Talker's work. ''I want him ready to run for his life in the Derby not the Derby Trial,'' he stressed. ''He went well enough to me and Gerald was even happier. He asked him to go from 1,200 metres out so it was understandable that he got a little tired. ''Also his work can be deceptive as he went with Peace Gallery who can be a terrific worker when he is allowed to relax in front, as happened in this gallop.'' Mosse asked Charming Talker to go and pick off Peace Gallery over the final 200 metres but his mount failed to respond and was a good half-length down on the line, leaving lingering doubts as to whether he has the genuine class to win a Derby. Meanwhile, John Moore's Derby contender, the much-vaunted Australian import Fastabob, passed his mandatory barrier trial in readiness for Saturday's big event. Fastabob was forced to trial after returning with a mild throat infection from his first run back from the virus when in the frame behind Kadbridge over 1,400 metres at Sha Tin. Moore elected to give Fastabob an easy trial and he went to the line hard held by jockey Darren Beadman in behind Precious Delights. Along with Right Way, who worked solidly on the equitrack yesterday morning, his presence should ensure an excellent contest in the Derby trial which, in turn, promises to provide a useful guide to the Derby proper. The second of yesterday's three barrier trials went to Derek Cruz's inconsistent performer Gallant Warrior who was disappointing behind 66-1 winner, Dong Win, at Sha Tin last time. Gallant Warrior was always going well yesterday as he and Win Label, who has been working well, pulled clear of their rivals. First trial: 1, PRECIOUS DELIGHT (A. Munro); 2, Goforit (M. Kinane); 3, Eminence (B. Marcus). Others (in finishing order): Fastabob, Ever Win, Spiritual, Hit The Town. Time: 1.04.9 (24.4). Distances: 1/2l, 1/2l. Winner trained by Derek Cruz. Second trial: 1, GALLANT WARRIOR (C. K. Chung); 2, Win Label (D. Beadman); 3, Beyond Control (B. Marcus). Others: Scan Lord, Jade, Leprechaun, Splendid Feeling, Dawn Raid. Time: 1.03.6 (23.4). Distances: 3/4l, 6l. Winner trained by Derek Cruz. Third trial: 1, AERAS (C. F. Chan ); 2, Top Lad (D. Beadman); 3, Cricket Lord (D. Gauci). Others: New Pegasus, Fun And Smile, Gladstonian, Fairmount. Time: 1.02.9 (24.1). Distances: 1l, 10l. Winner trained by John Moore. Moore then took the first two positions in the morning's final trial with Aeras and Top Lad in another uninspiring heat.