Lincoln soaked up a bit of the pressure and looped an effort high over the bar.
Chasetown skipper Ryan Wynter then tested the keeper and then Kieran Brown robbed Nicholson and forced the visiting keeper to make a scurrying save at his near post.
Curtis Pond then made a low save to his right, before Nicholson made a fingertip save to deny a long range effort from Jack Langston.
Lincoln took the lead from a corner in the 36th minute with Danny North powering home a header.
Chasetown levelled a minute into the second half. Kieran Brown was involved to force an error in defence and George Cater was on hand with the final touch.
The Scholars turned the screw and Cater's corner was headed goalwards by Wynter and met by a powerful Nicholson punch.
Wynter and Cater combined in the 68th minute as the skipper teed up the scorer of the first goal who turned quickly and drilled low through Nicholson’s legs.
Cater almost notched his hat trick in the final minute as Lucas Burnett squared from the bye line but Nicholson palmed the ball away strongly.
Deep into stoppage time, against the run of play, Lincoln pumped a free kick into the box and with almost the last touch of the game Michael Jacklin powered home the equaliser.