Having beaten Wycombe Wanderers 5-0 in their first pre-season fixture on Wednesday, Chelsea would have expected a similarly strong showing against Wimbledon at Kingsmeadow.
But Jose Mourinho's men were up against it as Alan Bennett scored inside the first minute and Matt Tubbs - who joined from Bournemouth last month - scored from the penalty spot shortly before the break.
Centre-back Terry - on as a half-time substitute - scored either side of Mohamed Salah's equaliser, while young midfielder Lewis Baker had a hand in all three goals.
Wimbledon made a flying start and Mark Schwarzer was picking the ball out of visitors' goal inside 40 seconds as Bennett leapt above Andreas Christensen to head home a corner at the back post.
Chelsea applied plenty of pressure in an attempt to get back into the game with midfielder Jeremie Boga looking particularly lively, but the away side were frustrated by Wimbledon's deep defensive line.
The away side upped their game after the break and Marco van Ginkel wasted a great chance to pull a goal back when he headed straight at goalkeeper James O'Shea.
Parity was restored with seven minutes remaining when Salah drilled home a left-foot half-volley after collecting Baker's pass.
