The defender's header had crossed the line before it was clawed out by Adam Bogdan in the 19th minute but referee Martin Atkinson waved play on and Bolton took the lead eight minutes before the break through Darren Pratley.
Djibril Cisse equalised three minutes after half-time but substitute Klasnic had the final say to lift Bolton out of the relegation zone and ensure Rangers will end the day inside it.
Source: PA
Source: PA