Aries Merritt of the U.S. reacts after winning the men’s 100m hurdles event at the Herculis Athletics Meet at Louis II stadium in Monaco, July 20, 2012. (REUTERS/Eric Gaillard)

MONACO, July 20 (Reuters) – American hurdler Aries Merritt and Nigerian sprinter Blessing Okagbare showed that they are in prime form and real threats to the big-name favorites at the London Olympics with impressive victories in the Monaco Diamond League meeting on Friday.

In the final warmup event before the Games, which begin in seven days, Merritt roared to yet another sub-13 second victory in the 110 meters hurdles while Okagbare chalked up a second successive sub-11 second run to beat another clutch of Olympic hopefuls in the women’s 100 meters.

Yelena Isanbeyva, hoping for a third successive Olympic pole vault title in London, had a night to forget, however, as she failed three times at her opening height of 4.70 meters.

The 2012 Olympic 110 hurdles has long been viewed as one of the potential highlights of the athletics program, based on another showdown between China’s Liu Xiang and Cuban Dayron Robles, but Merritt’s performances in recent weeks have ensured it will be much more than a two-man show.

After Liu pulled out injured from the final at a cold and wet Crystal Palace a week ago, Merritt won in 12.93 and he ran the same world leading time for the third time in three weeks on Friday.

Fellow-American Jason Richardson was second in 13.07, with Russia’s Sergie Shubenkov edging out another American, Beijing bronze medalist David Oliver, for third.

Okagbare is another looking to gatecrash the party at London and she underlined her potential to become Nigeria’s first Olympic 100 meters medalist with another personal best victory.

Having broken 11 seconds for the first time last week en route to taking the scalps of world champion Carmelita Jetter and Olympic champion Shelly-Ann Fraser-Pryce in London she improved again in more favorable conditions to post 10.96.

Tianna Madison, who will also run in London, was second in 10.99 with fellow American Jeneba Tarmoh third in 11.09.

There was a Jamaican victory in the 200 meters but it was not by the man the organizers or the crowd had hoped for following the withdrawal of world record holder Usain Bolt due to a hamstring injury.

Nickel Ashmeade, one of many hugely talented athletes to miss out on London via the cut-throat Jamaican trials where he finished fourth, blasted round the bend and held on just enough to win in 20.02 seconds.

Churandy Martina, now running for the Netherlands, was second in 20.07 and Wallace Spearmon, something of a surprise winner of the US trials, continued his timely improvement to take third in 20.09.

In the absence of another world record holder and red hot London favorite, Kenya’s David Rushida, two more talented young Kenyans, neither of whom were good enough to make their nation’s team for the Olympics, took center stage in the 800.

In a terrific finish 19-year-old Abraham Rotich ran a personal best one minute 43.13 seconds to just pip 17-year-old Leonard Kosencha as the Rift Valley production line shows no sign of slowing down.

Justin Gatlin, Tyson Gay and Ryan Bailey, the United States’ three entrants in the Olympic100, teamed up in the 4×100 relay and scorched to a season’s best 37.61 seconds on the same track where the Santa Monica Track Club, anchored by Carl Lewis, set a then-world record 37.79 21 years ago.