Leicestershire's Jigar Naik claimed a five-wicket haul to reduce Worcestershire to 294-7 on a rain-hit second day at New Road.
On a day in which nearly 60 overs were lost to the weather, the hosts resumed on 198-3 and added another 96 runs for the loss of four wickets, all claimed by an on-fire Naik.
Worcestershire fought back late on with Shaaiq Choudry on 15 not out and Thilan Samaraweera unbeaten on 92 at the close of play.
Naik, who had captured the wicket of Matt Pardoe on day one, claimed his first victim when play resumed when Alexei Kervezee was caught by Matthew Boyce for 35 to leave Worcestershire 227-4.
Neil Pinner was then out for a duck with the hosts on the same score, caught by Michael Thornley - his third of the game - after facing just six balls.
Michael Johnson hit 17 runs before being bowled by Naik, who then completed his five-wicket haul when Gareth Andrew went for a golden duck, caught behind by Naill O'Brien.
But Choudry came in to steady the ship with Samaraweera, with the pair adding 37 runs to take the score to 294-7 at the close of play.