NAIROBI, April 12 (Xinhua) -- Defending champion Edna Kiplagat of Kenya said she is focused on winning the Boston marathon next week and not worried about the World Marathon Majors (WMM) quest.

Kiplagat, who left Nairobi in buoyant mood for Boston, believes her training has been good enough to fend off the challenge from her rivals.

"I have done well in training and am happy to go through with any worries of an injury," she said. "Let me see what the rivals have to offer, but it will be a tough race to all."

However, the challenge has been reduced after America's Dathan Ritzenhein was forced to withdraw from the Boston Marathon due to injury.

"I'm devastated to be missing this year's Boston Marathon. After sustaining an SI joint injury last week in practice. It's incredibly difficult. I wish the best to all my competitors and the thousands of others who will be racing. I will be cheering you all on," he said on Thursday.

Kiplagat will be desperate to repeat her success of 2017. The veteran Kenyan can take a share of the World Marathon Majors lead on 41 points if she can claim the spoils on April 16.

Kiplagat put on a powerful display last April, breaking clear of her opponents with 10km to go and mastering the taxing Heartbreak Hill section to cruise through the wide streets of downtown Boston to victory.

She is joined in Boston by fellow Kenyan Geoffrey Kirui, who is also seeking to retain his status as Boston champion.

Kirui can move to 50 points in the men's Series leaderboard with victory, after being crowned world champion last summer in London, but the same goes for American Galen Rupp who already has victory in Chicago under his belt in this series.