'This is insane': Teen freak breaks second Usain Bolt record in a month

American teenage sprint sensation Erriyon Knighton has left the athletics world gobsmacked after bettering a second Usain Bolt record in less than one month.

The 17-year-old - who only recently ran 20.11 to break Bolt's World U18 record of 20.13 - went even faster in the semi-finals of the 200m sprint at the US Olympic trials.

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Knighton signalled his intention in the first round with a then-personal best of 20.04 to beat world champion Noah Lyles, who ran 20.19.

But the former college football star set another stunning personal best in the semi-finals - clocking an astonishing 19.88 to break Jamaican Olympic legend Bolt's 19.93 world junior record.

The extraordinary achievement left athletics fans in disbelief.

Teen lays down stunning Olympics marker

The American teen stunned onlookers four weeks weeks ago after eclipsing an U/18 record held by Bolt.

Knighton ran down Olympic 100m favourite Trayvon Bromell on the straight to win the 200m meet in a stunning 20.11 seconds, shaving 0.02 seconds off the time Bolt recorded in 2003.

Bromell, who has run the year's fastest 100m race at 9.88 seconds, finished a close second to Knighton in 20.20.

This was the previous best 200m time since 2015.

Meanwhile, Grant Holloway fired a warning shot to his Olympic rivals after coming within a whisker of breaking Aries Merritt's 110m hurdles record of 12.80sec set in 2012.

America's 23-year-old champion clocked a world-leading 12.81sec in the semi-finals at Eugene's Hayward Field, before winning the final in 12.96sec ahead of Devon Allen in 13.10sec and Daniel Roberts in 13.11sec.

There was a similarly emphatic victory for Gabby Thomas in the women's 200m, with the 24-year-old Harvard graduate surging home in 21.61sec - the fastest time in the world this year.

Only the late Florence Griffith-Joyner - whose world record of 21.34sec from the drug-tarnished 1988 Olympic Games remains intact - has ever run faster.

Thomas had already set world-leading times in the opening two rounds of the 200m.

However, she saved her best for last, taking the lead coming off the bend and powering home, arms aloft in celebration.

Jenna Prandini took second in 21.89 while youngster Anavia Battle took third in 21.95. Veteran sprint queen Allyson Felix, already assured of a place at the Olympics in the 400m, finished fifth.

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