But Micky Adams' side did claim a welcome boost after the final whistle courtesy of Portsmouth's shock 2-1 reverse at home to Sheffield Wednesday which put the Foxes in pole position with four games left.
The Foxes, unbeaten in 13 games, and chasing a club record 26th League win of the season, had to fight hard for a share of the spoils and needed a 75th minute equaliser from Trevor Benjamin.
The Millers had earlier taken the lead courtesy of a 54th minute goal from Irishman Alan Lee.
Chances were at a premium in the first half with Mark Robins going close with a deflected effort after 16 minutes.
Soon after substitute Andy Impey, on for Gerry Taggart, saw his dangerous cross fall onto the roof of the net before Robins was a hair's breadth away from connecting to an excellent cross from Gareth Farrelly.
On 28 minutes Martin McIntosh blazed a chance over before the Millers had appeals for a penalty turned down when the ball seemed to hit Frank Sinclair on the arm.
An effort by Chris Sedgwick had Foxes keeper Ian Walker scrambling anxiously across goal and just before the break the Millers had another penalty claim turned down after Lee fell under the challenge of Sinclair.
After the break City, attacking the railway end where their 3,300 supporters were housed, signalled their intentions by forcing a couple of early corners.
However, it was the Millers who had the half's first opportunity when Sedgwick's hanging cross was met by Lee whose looping header struck the woodwork before bouncing to safety with ex-Foxes star Robins waiting to pounce.
In the 54th minute Lee fared better when he broke the deadlock with a brilliant downward header after connecting to a teasing McIntosh cross.
Shortly before the hour mark an excellent Guy Branston tackle denied his former club before James Scowcroft blasted a good opportunity over.
In the 74th minute Robins spurned a great opportunity to kill the game off when he fired over with the goal at his mercy and the Millers were made to pay immediately after.
Paul Dickov bamboozled the Millers defence before sending over a cracking centre which was superbly headed home by Benjamin.
Try as they might the Foxes couldn't grab that all important second goal but they did have some consolation thanks to the unexpected events at Fratton Park.