Yamashita was hospitalised after suffering a major crash at the wheel of Rookie Racing’s Toyota GR Supra at Suzuka’s 130R corner on the opening day of private SUPER GT manufacturer testing in late January.
He was released from hospital the following day, but the damage to the car was severe enough to prevent Rookie from participating in February’s Okayama test.
Yamashita had been hoping to recover in time to participate in this week’s final group manufacturer SUPER GT test at Suzuka, as well as the two days of Super Formula running on March 6-7 that follow this weekend’s Fan Thanks Day event at the same track.
However, it’s understood that Yamashita will instead sit out both Suzuka tests, and is also likely to miss the opening official SUPER GT test at Okayama on March 11-12.
The 27-year-old is now targeting a return to the cockpit in time for the final SUPER GT test of the winter at Fuji Speedway on March 25-26.

Kondo Racing has not yet announced a replacement for Yamashita for the Suzuka Super Formula test, but Ukyo Sasahara appears to be the most likely candidate to step in.
Two-time race winner Sasahara is without a full-time drive in Super Formula this year after losing out on a place at TOM’S to Giuliano Alesi following his off-season switch from Honda to Toyota.
Yamashita’s SUPER GT team-mate Kazuya Oshima meanwhile is expected to pilot the #14 Rookie Toyota solo for both the Suzuka and Okayama tests.
Missing the Suzuka test comes as a major blow to Yamashita’s hopes of a return to form in Super Formula, as the two days of running mark the only chance for drivers to familiarise themselves with the upgraded SF23 package before the first round at Fuji in April.
Exact details of the Japanese driver’s injuries remain unclear, but he posted an image of himself undergoing rehabilitation on his Twitter account last week.