French striker Jeremie Aliadiere has joined West Ham on loan from Arsenal.
The 22-year-old joined Celtic in July on a year-long loan but has decided to move back to the Premiership, with the Hammers taking over the deal.
Aliadiere made only two appearances for the Glasgow side, both as a substitute against Artmedia Bratislava in the Champions League qualifying round.
"I am very disappointed this has not worked out the way I thought it would," the Frenchman said.
A Celtic spokesman said: "Unfortunately, things didn't work out in a football sense for Jeremie and he wanted to return to England."
Even after a long-term injury to Chris Sutton, Aliadiere found himself behind John Hartson, new signing Maciej Zurawski, and in-form youngsters Shaun Maloney and Craig Beattie.