Bulli runner Ryan Gregson is adamant his London Olympic qualifying campaign is still on course despite an injury setback.The 21-year-old suffered a small calf tear in training last week, ruling him out of Saturday’s 1500m event at the Sydney Track Classic. The scare came after Gregson (pictured) pulled up with tight muscles following an 800m event in Hobart where he finished third, despite having his heel clipped and stumbling during the race.As a result, Gregson will be denied his first major chance to meet the London Games qualifying mark of 3.35.50min at the Sydney Olympic Park athletics track on Saturday.‘‘It’s disappointing, but such is life,’’ he said. ‘‘There’ll still be plenty of opportunities to qualify.‘‘It puts me back a week or so, I would have liked to have made the time in Sydney to take the pressure off, but it won’t mean too much in the long run.‘‘It just means I’ll probably have to do [the Olympic qualifying time] overseas.’’Gregson is confident of being fit for next month’s Melbourne Track Classic, but expects the race to unfold without the pacesetters needed to ensure the race is run at an Olympic standard.While he was hopeful of making the time for London early in his 2012 campaign to take the pressure off, Gregson will focus on his rehabilitation and return to training later this month.He is now in Ballarat, Victoria, after flying to Melbourne to undergo specialist physiotherapy treatment on his leg.The Australian record holder over 1500m, Gregson will return to Wollongong to continue training after the Melbourne event, before heading to the United States for an intensive training camp.Gregson will then focus on a likely race in Philadelphia as a lead-up to the Diamond League meets in Doha and Shanghai in his bid to ensure a ticket to London for the July Games.The latest frustration for Gregson comes after an injury-plagued 2011 season, where he battled calf and foot problems.Gregson withdrew from the race in Perth last weekend, after almost falling in Hobart.He recovered after stumbling to hit the lead in the closing stages, but was then overpowered in the sprint to the line after using most of his energy to make up lost ground.‘‘I was lucky not to fall, I only just stayed on my feet,’’ he said.‘‘I felt it was a bit tight after the race, but it was when I was training that I felt it sore and found out I had a grade one tear.’’