Joe Gardner had a debut to forget as he was sent off as Lincoln were held to a 1-1 draw by Cambridge.
The Nottingham Forest teenager, on loan at Sincil Bank, was on the pitch for just four minutes before being show a red card for a collision with James Brophy.
Michael Skubala’s side missed the chance to close the gap in the League One play-off race after Freddie Draper’s effort was cancelled out by James Gibbons.
Sunderland loanee Nathan Bishop made a good save to keep out Draper’s early effort.
But the striker made no mistake as he poked home a rebound in the 17th minute after another shot was blocked.
Kelland Watts did well to clear an effort off the U’s line after a mix up at the back.
Gibbons’ deflected strike restored parity on the stroke of half-time.
Josh Stokes should have done better when he headed straight at Imps’ stopper Zach Jeacock from point-blank range.
Draper fired a strike wide before Gibbons saw a shot deflected into the side netting.
James Collins’ back-post header was blocked before he hit the rebound over.
Jeacock did well to push Stokes’ strike away from danger.
Lincoln’s hopes of a late winner were dashed when Gardner was sent off.
The struggling U’s nearly nicked it at the end when Watts saw his free header denied by Jeacock.
