Former IndyCar driver James Jakes has been replaced by 2015 Le Mans 24 Hours LMP2 winner Matt Howson at Manor for this weekend's Nurburgring World Endurance Championship round.
Howson will drive alongside Tor Graves and Antonio Pizzonia in the #44 Manor ORECA-Nissan 05 LMP2 entry.
Manor sporting director Graeme Lowdon was unable to discuss the absence of Jakes and that of Will Stevens, who has been replaced by Pizzonia, from this weekend's event.
Nor could he say whether Pizzonia or Howson would be racing for the team in subsequent WEC rounds.
He explained that Howson was an obvious choice as a late stand-in courtesy of his experience in an ORECA 05 with the KCMG team.
The Briton is the latest in a line of former Manor single-seater drivers to return to the team during its first season in endurance racing.
Howson raced for Manor in the 2001 Formula Renault UK Winter Series.
The line-up of Roberto Merhi, Richard Bradley and Matt Rao in the #45 Manor ORECA remains unchanged.