The two, who have confirmed missing out on the Kenyan trials this weekend, hope they will convince the selectors to give them wild cards should they perform extremely well at the Diamond meeting in Paris on July 1, reports Xinhua news agency.
Mucheru said he has fallen behind his schedule and is struggling to get the pain out of his leg, which he injured in training.
On the other hand, Saina, who represented Kenya at the 2015 World Championships and 2016 Rio Olympic Games, is battling a nagging Achilles injury
Saina, who is based in the United States, said she has just returned to training and was hopeful, she will shake off the rust and be ready for the World Championships.
"I am excited to be healthy again. Today, I did 11 miles run this morning, it has been a long journey but happy to be fully recovered. Let the training begin," she said on Monday.
Mucheru, who is also the Africa 400m hurdles champion, wants three more races to gauge his preparedness and is hopeful he will have no problem making the Kenya team.
Only one athlete, world 400m hurdles champion Nicholas Bett, has run the required qualifying time and Kenya has the chance to name up to three athletes in the sprint hurdle event.
Another athlete seeking the required mark is Haron Koech. The qualifying mark has been set at 49.35 seconds.
"I have been feeling pain deep inside the bones in both of my legs and the doctor hinted that it stems from the spikes I have been using since 2014," said Mucheru.
"I have at least two more weeks to full recovery hence not possible to compete at the trials," he added.
Bett, Koech and Mucheru held their pre-season training in Kenya before moving to Dominican Republic under two times Olympic 400m hurdles champion Felix Sanchez.
Bett and Mucheru opened their season in Doha where they finished fourth and seventh in 49.70 seconds and 50.61 respectively.
Bett moved to Shanghai with Koech but they didn't perform well, finishing seventh and eighth respectively.
However, Kenya has no qualifier in the women's 400m hurdle race.
Maureen Jelagat, who has represented Kenya over the 400m hurdles at the 2012 London and 2016 Rio Olympics, is the likeliest candidate to gain the qualification.
She will be making a long shot in both the 400m and 400m hurdles events during the Kenyan trials.
( 453 Words)