IPC World Athletics: McKillop and Smyth in Friday Doha heats
Triple Paralympic gold medallist Michael McKillop joins Jason Smyth in starting his IPC Athletics World Championships challenge on Friday.
McKillop, 25, will begin the defence of his T37-38 800m title when he runs his heat at 16:01 BST in Doha.
The four-time world champion's qualification for Saturday's final will be expected to be a formality.
"I had injury problems at the start of the year but I have now put that behind me," said Glengormley man McKillop.
McKillop, who has a mild form of cerebral palsy, has not been beaten in paralympic competition since taking a World 1500m silver medal in 2006.
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The same championships in Assen saw him win his first world title when he triumphed in the 800m and the Irish athlete took his first Paralympic gold medal in Beijing two years later.
McKillop clinched a second world 800m title in Christchurch in January 2011 and was only denied a double at the championships in New Zealand after finishing first in the 1500m final, because of the dearth of entries in that race.
However, double success did follow for McKillop a year later at the London Paralympics and the Northern Irishman achieved further doubles at the 2013 IPC World Championships in Lyon and at last year's European Championships in Swansea.
McKillop's injury troubles
After his London triumphs, McKillop broke his wrist a few weeks later when he fell off a bike while on holiday in Rome and his preparations for 2014 were also hindered by a foot injury.
This year's injury also followed a mishap as the county Antrim man suffered ligaments and tendon damage in his left foot following a slip.
"The last couple of years have all been down to injuries or other small things I have done," McKillop told BBC Sport.
"This year's injury needed a lot of recovery and I didn't really start training until the middle of June.
"But I'll be expected to win gold and that's what I have to live up to in Doha."
McKillop will also defend his T37 1500m in Doha in the straight final on Friday, 30 October.
Smyth will compete in the T13 100m heats on Friday afternoon (16:25) and will be expected to comfortably progress to Saturday's final.