TOKYO - A season's best performance and the fastest qualifying time of the round powered the United States to the final of the men's 4x400m relay in its heat at the Olympic Stadium on Friday.

Trevor Stewart, Randolph Ross, Bryce Deadmon and Vernon Norwood were quick off the block and came into the first changeover second but then took a lead they never relinquished as smooth changeovers took them to a time of 2:57.77.

Botswana finished second ahead of Trinidad and Tobago, and showed that it could be a real threat for a podium finish at the weekend.

In the second heat, Poland, which had already won gold in the inaugural Olympic 4x400m mixed relay, produced a brilliant come-from-behind win in a season's best time of 2:58.55.

Also through to the medal round is Jamaica, who also clocked a season's best of 2:59.29 to finish second. Belgium's third-place performance was also enough for it to advance.