MARTIN Pipe, the champion jumps trainer in Britain, has been playing a different role this season, languishing in fifth place on current standings, with his 160-strong yard in the West Country still in the grip of a menacing virus. But the industrious Pipe, who claims to be working harder than ever to bounce back, still has ambitious plans for the big races over the Christmas period. Pipe has announced plans to send the exuberant jumper Rolling Ball to Kempton Park for the King George VI Chase tomorrow, setting up an intriguing clash with The Fellow, the French-trained favourite, and Young Hustler, an exciting winner of the BetterwareCup at Ascot. Also booked for the traditional festive season feature is Barton Bank, a promising young jumper trained by David Nicholson. Rolling Ball, winner of the Sun Alliance Chase in 1991 but plagued by leg injuries almost ever since, had been 5-1 favourite with the sponsors for the Coral Welsh National on Tuesday, but the firm have now removed the gelding's name from their list and offer him at 4-1 ''with a run'' for the Chepstow race. The gelding, set to be partnered by Richard Dunwoody, is on offer at 14-1, from 25-1, for the King George, a price-trimming exercise affected by the news of Pipe's decision earlier this week. Reporting that Rolling Ball had schooled well since his heavy third-fence fall in the Gold Cup at Newbury late last month, Pipe pointed out: ''This is not a change of plan going to Kempton. We had two options, and we have chosen the King George option. ''I know it is a tough race, but he's a decent horse and it is worth having a crack at the big race with him,'' the trainer said. ''As far as the Welsh National is concerned, I still haven't finalised plans. Riverside Boy is there, and so are a few othersof mine, but nothing has been settled yet.'' Corals have clipped Riverside Boy to 9-2 favouritism from 5-1 for the Welsh National, with Party Politics, the 1992 Grand National winner, at 7-1, the promising Indian Tonic 8-1, and Cool Ground, winner of the Welsh staying test in 1990, next at 10-1. The Betterware Cup (formerly the SGB Chase) was won in tremendous style by Young Hustler, whose performance under topweight was, in my view, the best King George trial seen in recent weeks. ''He is a horse who keeps surprising me,'' admitted Carl Llewellyn, his regular partner. ''When I asked him to move up on the outside of Latent Talent on the turn, he found another gear.'' Publicity-shy Nigel Twiston-Davies, a reluctant occupier of the limelight, believes Young Huster's toughness will stand by him in the run up to the King George, which will be his third major race in consecutive weeks. ''I think he's probably as tough as Mrs Muck (his former top-class staying hurdler), and she was pretty tough,'' said Twiston-Davies. ''He has come out of the Ascot race very well. He won the Arlington Chase, the Scilly Isles and the Great Yorkshire Chase on consecutive Saturdays last season and he seemed to thrive on it,'' the trainer said. The other interesting King George news is that Nicky Henderson has decided to send Travado to tackle the three miles in the big race at Kempton, by-passing a return clash in Wetherby's Castleford Chase with Jimmy FitzGerald's Sybillin, who has done well since his exciting Tingle Creek Chase victory at Sandown Park. Only if the ground at Kempton is heavy will Travado be switched to the two-mile contest at Wetherby, according to Henderson. Bookmakers Hills are cautiously offering 10-1 about the chaser in their ante-post market on the King George.