Van der Mark broke his leg while training on a mountain bike in March, forcing him to undergo surgery just weeks before the start of the new campaign in Spain.
With little time to complete a full recovery, the Dutch rider will sit out the April 8-10 Round of Aragon, leaving the bike to Ukrainian rider Mikhalchik.
Mikhalchik has already ridden the WSBK-spec M1000RR for a recent test in Barcelona and will continue to race the bike at the Dorna-supported test in Aragon on Monday and Tuesday before making its racing debut at the same track.
“It was a tough decision but unfortunately I won’t try to ride at Motorland Aragon,” said van der Mark.
“Right now we have to be smart and stay calm because that’s the only way forward for my recovery. I really miss working with the team and riding my BMW M1000RR, but for now my focus is on be fit again as soon as possible.
Ilya Mikhalchik, BMW Motorrad WorldSBK Team
Photo by: BMW Motorsport
Mikhalchik will be joined in Aragon by 2020 runner-up Scott Redding, who is new to the BMW factory team this year after spending the past two seasons with Ducati.
The British rider set the seventh fastest time in Barcelona testing last week, a second and a half behind leader Toprak Razgatlioglu on the Yamaha.
Mikhalchik, who is racing in the Spanish Superbike Championship this weekend, finished the test in 16th place – more than a second off the pace of his more experienced team-mate Redding.
BMW’s factory WSBK effort is supported by a pair of satellite bikes run by the Bonovo MGM team, with Loris Baz and Eugene Laverty signed as the team’s two riders.