According to data compiled by Oddschecker, the Chilean is now as short a price as 6/1 for an imminent departure from the Etihad.
It comes after Manchester City slipped further behind Chelsea in the race for the Premier League title with a 1-0 defeat to Burnley at Turf Moor.
The Sky Blues now face Barcelona at the Camp Nou in the Champions League on Wednesday looking to overturn a 2-1 first-leg loss in Manchester.
Suffer defeat to the Catalans and the price on Pellegrini exiting the Etihad sooner rather than later could shorten even further.
Premier League front-runners
The 2/1 favourite Pearson is under ever-increasing pressure after a 0-0 draw with Hull City left Leicester City seven points adrift with 10 games remaining.
Allardyce, who is as short as 3/1 to leave Upton Park, also looks set for the chop after picking up three points from the last 27 available in the Premier League.
Big Sam is out of contract at West Ham in the summer, but owners David Gold and David Sullivan could opt to part company with the former Bolton and Newcastle gaffer sooner than that if results continue to nosedive.