Moscow - Grenada's Olympic and world 400 metres gold medalist Kirani James and his predecessor as world and Olympic champion LaShawn Merritt set up a mouthwatering clash in the 400m final after winning their semi-finals at the World Athletics Championships on Monday.
James, 20, and Merritt, though, may have to keep an eye out in Tuesday's final in Moscow on fast-improving Saudi Arabian Yousef Ahmed Masrahi.
The 25-year-old, who is bidding to give Saudi Arabia only their second ever world championship medal, won his semi-final with a personal best and new national record of 44.61 seconds - the second fastest time of the semi-finals.
Merritt, who served a 21-month doping ban before subsequently winning a court case allowing him to compete in last year's Olympics, almost slowed to a walk halfway down the straight and still posted the fastest time of 44.60sec.
"It was a question of conserving enough energy for the final," the 27-year-old American explained.
"I'm ready to start the final if it was right now. I trained to win the title and I feel as if I am ready to win. I expect an interesting final on Tuesday."
James, who two years ago became the youngest ever world or Olympic champion when he won the world crown at 18, was pushed harder in his semi-final but won it in a time of 44.81sec.