Jess Clarke gave the visitors a 62nd minute lead before a goalmouth scramble resulted in Blues snatching an equaliser with five minutes to play.
In what was a scrappy opening to the game, Blues had two early efforts as Jo Potter tested visiting goalkeeper Karen Bardsley with identical long-range free-kicks.
Lincoln grew into the game though and began to play some nice football despite blustery conditions naking it difficult for either side to get the ball down and play.
Blues were then forced into an early change as Isobel Christiansen took the full force of a Sophie Walton clearance in the face. The midfielder tried to carry on, but was soon replaced by Melissa Lawley.
However, Blues should have taken the lead just before half-time. A mix-up in the Lincoln backline saw a bouncing ball evade Casey Stoney and find Williams 20 yards out. The striker drove into the box before shooting, but she dragged her effort just wide.
Half-time saw Emily Westwood make way for Kirsty Linnett as Blues looked to inject more pace on the right-wing.
But the change seemed to invigorate the visitors who settled quicker than Blues in the second half. Carla Cantrell fired an ambitious volley over and Kerys Harrop made a last-ditch tackle to cut out a through ball to prevent Precious Hamilton from getting in behind the Blues defence.
In the 62nd minute, Clarke forced Marie Hourihan into a fingertip save with an effort from range and from the resultant corner, Lincoln took the lead. Cantrell’s delivery was initially cleared, but when Hamilton put the ball back in, Clarke turned quickly to score on the spin.
Hamilton then forced Hourihan into another save before Blues came back into the game. Potter tried an audacious free-kick which nearly caught Bardsley out and shortly afterwards Linnett nodded over the stranded goalkeeper, but Unitt couldn’t connect with the loose ball to score.
Cantrell missed a great chance to seal the win when she failed to properly connect with a header from six yards out and it would prove to be costly.
With only five minutes left on the clock, the impressive Lawley jinked her way down the left wing before crossing to the back post. Linnett strode on to the ball to fire across goal and a wicked deflection off Stoney left Bardsley helpless as Blues levelled.
And in the last minute, Blues could have won the game when Williams’ brilliant run ended with a pass to Lawley who fired wide when a goal looked likely.
Birmingham City Ladies: Hourihan, Weston, Harrop, Unitt, Bassett (c), Moore, Potter, Westwood (Linnett, 45) Simpkins (Wilkinson 71), Christiansen (Lawley 29), Williams.
Subs (not used): Torkildsen, Earps, Ballard, Haines
Goals: Linnett (85)
Bookings: Unitt, Weston
Lincoln Ladies: Bardsley, Stoney (c), Harris, Hamilton, Cantrell, Allen, Clarke, Walton, Harris, Turner, Roberts (Bowden, 69)
Subs (not used): Horwood, Kay, Bradley
Goals: Clarke (62)
Player of the match: Melissa Lawley