'This is where we turn to head back,' Will told Tug. A tall pole had been hammered into the ground to mark the spot. The little horse studied the marker with interest.

Will turned and looked back towards the oasis. It was now out of sight, hidden by the undulating ground, but he knew it was four kilometres distant. Four kilometres out, four back. Eight in all. He had tried for twelve, then ten. Finally, he had to settle for an eight-kilometre race course. He hoped it would be far enough for Tug's stamina and staying power to assert itself over Sandstorm. It would be a close thing, he knew.

The Arridi horse was definitely faster over a short distance. For the first kilometre or two, he would leave Tug behind. But then the Ranger horse would start to reel him in as the Arridi stallion began to slow and Tug maintained his speed.

'We'll win it on the back leg,' Will told Tug. He had decided to walk the horse over the course to familiarise him with it, and to give them both a chance to spot any hidden holes or unevenness that might bring them down.

Tug shook his head and whinnied softly, At times like this, Will was never totally sure that the horse was just responding to the sound of his master's voice. It often seemed that he understood every word Will said to him and was agreeing or disagreeing.

Or we'll lose it on the back leg, Will thought. But he didn't speak the thought aloud in case it put negative concepts in Tug's mind. He hoped that the second four kilometres would give Tug the chance to make up the distance he'd lose on the first half of the race. Then, when they drew level with the Arridi horse and rider, another contest would begin.

Horses like Tug and Sandstorm hated to lose, hated to have another horse ahead of them. As Tug drew alongside Sandstorm, Will knew, the Arridi horse would dig deep for a greater effort – to put the little foreigner back in his place. Tug, meanwhile, would be straining for extra speed to pass the Arridi horse. It was then a matter of judgement for the two riders, to pick the point where they should let the horses' have their heads.

Too soon and the energy and speed would peter out before the finish line. Too late and there wouldn't be time to overtake. Each rider would do his best to force his opponent into going too early. The moment had to be just right or the result would be failure. Will frowned thoughtfully. He'd watched as Hassan had put Sandstorm through his paces. But he was sure the Arridi rider was holding something back.

As they walked back towards the oasis Tug's head butted him in the shoulder, sending him staggering.

Stop worrying, the horse seemed to say. I know what I'm doing, even if you don't.

'Just don't go too soon, that's all,' Will cautioned him. Again, Tug tossed his head disdainfully.

They walked slowly back into the oasis. Unlike Hassan, Will had no need to familiarise himself with his mount's little peculiarities. He and Tug knew each other's ways back to front and inside out. A curious crowd of Bedullin watched them as they entered the camp. It was early morning and the race was set for late that same afternoon, when the full heat of day had passed.

He knew that there had been a lot of betting on the race. It was impossible not to hear conversations in the camp, even though he tried to appear aloof to such matters. He also knew that most of the betting wasn't about the actual outcome of the race. It was about the margin by which Sandstorm would win. The Bedullin were familiar with the beautifully formed Arridi stallion that Hassan would be riding. It seemed that none of them gave the shaggy little barrel-shaped horse from the north any chance of winning.

Even though Will had the utmost faith in Tug, faced with such universal disbelief, he found it hard to keep his spirits up. Yet he had to believe they could win – that they would win. The prospect of losing was just too awful to contemplate. He had been too impulsive, he thought, to risk losing Tug in such a way. Yet time and again throughout the day, when he racked his brains to think of what else he could have done, he came up with no answer. If he were to get Tug back, he would have to risk losing him.

The thought tortured him through the long, heavy hours of the middle of the day. Then, as the sun began to slant down, and the shadows of the palms stretched out further and further, it was time.

His face was grim and set as he led Tug through the oasis to the start line. Hassan was waiting, mounted on the beautiful palomino, by the line that had been gouged in the sand. Like Will, who had discarded his cloak for the race, he wore shirt, trousers and boots, and a kheffiyeh. The headgear would protect the riders' faces from flying sand and dust during the race. He nodded a greeting as Will and Tug moved towards the starting line. Will nodded back. He didn't speak. He couldn't bring himself to wish Hassan good luck. He didn't want Hassan to have anything but bad luck. If Hassan managed to fall off Sandstorm in the first fifty metres and break a leg, Will wouldn't mind in the slightest. Yet looking at the Bedullin youth's easy seat on the horse, as Sandstorm moved nervously, prancing slightly, ears pricked with eagerness for the coming contest, it didn't seem likely. Hassan seemed glued to the saddle, an integral part of the horse.

Will put his foot in the stirrup and swung up astride Tug.

'This is it, boy,' he whispered. The horse tossed his head. Will drew one end of the kheffiyeh across his face, and twisted the other end over it to hold it in place. Now only his eyes showed, through a narrow slit. The rest of his face was covered. Beside him, Hassan did the same.

Sandstorm pawed the ground eagerly, kicking up small clouds of dust. Beside him, Tug stood stolidly, all four feet planted firmly. The difference between the two horses was all too obvious: one prancing, eager and light-footed, his coat groomed till he gleamed; the other solid, barrel-chested and shaggy. More money changed hands as last-minute bets were made.

'Riders, are you ready?' Umar stepped forward as he called them.

Hassan waved one arm. 'Ready, Aseikh!' he called. The Bedullin cheered and he waved to the watching crowd.

'Ready,' Will said. His voice was muffled behind the kheffiyeh and he had to force the word out through a throat constricted by anxiety. There was no cheer this time. As far as he knew, nobody had bet on him – only the distance by which he'd lose.

And that was hardly something they were going to cheer about.

'Move to the line. But remember, if you cross it before the start signal, you will have to turn and go back to cross it again.'

Hassan edged Sandstorm forward, crabbing him sideways. This was a tricky moment for him. With the horse prancing and excited, he had to hold back a metre or two from the line to make sure he didn't cross prematurely. Will nudged Tug and the little horse moved quietly to the line.

'Hold there, boy,' Will said quietly. Tug's ears twitched in response and he stopped, his forehooves only centimetres from the line. One of the Bedullin, who had been assigned the task of monitoring the start line, crouched and peered closely at the horse's hooves, then straightened as he realised Tug wasn't infringing. But he kept his eyes riveted on the line and Tug's feet. Seeing it, Will touched Tug with one toe.

'Back up, boy,' he said. He wasn't willing to take the risk that the judge might be overeager to penalise him. Tug obediently retreated one pace. A few of the Bedullin frowned thoughtfully. The horse was well trained. Was there more they should know about?

'There will be no interference between the riders. If either of you interferes with the other, he will automatically lose.'

The two riders, now intent on the course that stretched out before them through the desert, nodded their acknowledgement. There were marshals stationed along the course to make sure neither of them cheated.