By Nick Mulvenney
RIO DE JANEIRO (Reuters) - Reigning champion Kirani James clocked a season-best 44.02 seconds to lead LaShawn Merritt and Wayde van Niekerk into the final of the 400 meters at the Rio Olympic Stadium on Saturday.
The Grenadian got off to a great start and managed to hold off American Merritt, his predecessor as Olympic champion, coming into the home straight before both eased up knowing the first two home were guaranteed a spot in Sunday's final.
"In a race like that it is always tough," James said. "I had the inside lane so I could see what LaShawn was doing, and now I will just relax a bit and get some rest.
"Tomorrow is going to be a dog fight"
Merritt, who was unable to defend his title in London after suffering a hamstring injury in the heats, clocked 44.21 for the second best time of the semi-finals and suggested he had plenty in reserve.
"It was cool," he said. "First round handled it well. 45.2, not too much energy put out. Great track, nice atmosphere. I feel good."
Van Niekerk, who won a thrilling race between the trio to win the world title in 43.48 in Beijing last year, also got off to a flyer but, perhaps keeping something in reserve, eased up over the last 20 meters to finish in 44.45.
Trinidad and Tobago's Machel Cedenio served a reminder that the final will not be a three-man affair when he overtook the South African at the line to win the heat in 44.39 meters.
"I'm grateful for an injury-free race," said Van Niekerk. "These are quality guys in this event. I'll have to dig deep to beat them."
James's compatriot Bralon Taplin won an extremely tight third heat in 44.44 seconds ahead of Britain's Matthew Hudson-Smith (44.48) and Ali Khamis Khamis of Bahrain (44.49).
Hudson-Smith and Khamis Khamis had never run faster while Botwana's Karaba Sibanda (44.47) also posted a personal best to finish third behind James and Merritt and complete the line-up for the final.
"Eight men will line up in the final, I say this every final," Merritt added. "You never know what's going to happen in the Olympic Games. People step up but I'm expecting it to be a fast final."
(Editing by John O'Brien)