Ben Chorley faces a quick reunion with his former employers after joining Stevenage.
The centre-half made a surprise move to Boro at 9pm on deadline day and first up are the O's.
Boss Gary Smith moved for Chorley after learning Jon Ashton had been ruled out for the rest of the season.
Ashton was on the comeback trail following a long spell out injured when he suffered a ruptured Achilles in training last week which required an operation.
Loanee Robbie Rogers has returned to Leeds and fellow winger Rob Sinclair has moved to Salisbury City since Boro's last outing, a 2-1 defeat by Doncaster three weeks ago.
On-loan Southampton striker Sam Hoskins is pushing to make his full debut having come on as a late substitute against Rovers.
Shaun Batt will be added to the Orient squad for the trip.
The O's boosted their firepower on deadline day by snapping up the striker on loan from Millwall for an initial month.
Boss Russell Slade made his move as top scorer Kevin Lisbie remains on the sidelines with a hamstring injury.
Slade must decide whether to start Batt or stick with Charlie MacDonald and David Mooney, who drew a blank in the goalless draw with Swindon in midweek.
He may decide to hold the new boy back for Tuesday night's Johnstone's Paint Trophy area final against Southend, for which MacDonald is cup-tied.
Fellow forward Michael Symes has joined Burton on loan while centre-half Ben Chorley could be in opposition after joining Boro on deadline day.
Skipper Nathan Clarke is still building up his fitness following an ankle injury.