Hampshire's Billy Mackenzie finished fourth in the British 125cc MotoCross Grand Prix at Hawkstone Park - just a week after dislocating his right ankle in a spectacular racing tumble in Germany.

The teenager from Tichfield had to ride with a specially adapted footpeg on his Dixon Yamaha made up by team manager Steve Dixon and Mick Whitlock.

Mackenzie had spent all week with top motor cycle physio Brian Simpson, who just a month earlier had helped repair a dislocated shoulder, the result of another high-speed crash.

To get fit for Hawkstone Park, Mackenzie had to spend time in an oxygen chamber and also underwent magnetism and laser treatment.

The Swanmore-based team couldn't believe their bad luck when Mackenzie crashed again at Hawkstone while lying fourth in the first of the 125 races.

Mackenzie explained: "During the race I just couldn't jump properly. I didn't want to put my foot down in right-hand corners and then at the top of Hawkstone Hill, I spun out and fell."

But the young Scot pluckily remounted after having to use his left foot to kick over the 250 four stroke machine - not as Dixon pointed out later, a natural action. He still managed to get the thing going again and gallantly finished 20th for one Championship point.

With the help of pain killers, Mackenzie came out for the second race and remarkably made a good start, tucking into second place behind the American Jeff Dement.

Mackenzie said: "I had the red mist come over me and I wanted to pass him and go on and win. But every time I jumped I had pain, so I decided to play it cool and just ride for the points."

Championship leader Stephen Sword passed Mackenzie and went on to win the race from Dement with Mackenzie dropping back to fourth.

He said: "This is a six-week injury and I wasn't racing at my full capability. I might have to give the next event at Culham a miss to get fit for the GPs."

Manager Dixon said: "Considering he was riding on one leg, Billy did a tremendous job to come away with 24 points. He now has a few weeks to prepare for the next rounds which might help the healing process."

Mackenzie, runner-up last year, is still lying in a strong fourth place in the championship although he is now 90 points behind defending champion Sword.

Another Dixon Yamaha rider Mark Jones took eighth and ninth places in the Open Class races, both won by Gordon Crockard on a Honda.