Bolton's Radhi Jaidi prevented Chelsea from extending their Premiership lead with a last-gasp equaliser.
The Tunisian sent his low drive past Peter Cech after pouncing on Nicky Hunt's nod down from a free-kick.
The home side took the lead after just 37 seconds when Damien Duff rounded Bolton keeper Jussi Jaaskelainen after a sublime pass from Frank Lampard.
Tiago made it 2-0 with a deft volley, before Kevin Davies' header and Jaidi's late show ruined Chelsea's day.
The start of the game was delayed by 30 minutes because of a traffic accident but the home side were soon at their best through Lampard's quick thinking and Duff's quick feet.
The Republic of Ireland international raised his market value furthermore by coolly slotting past the on-rushing Bolton keeper before many of those at Stamford Bridge had even taken their seats.
Ricardo Carvalho, who has yet to score his first goal for the club, came very close to adding a second, but narrowly missed when he sidefooted past Jaaskelainen's left-hand upright.
Defender John Terry came even closer moments later but saw his header fly fractionally over the crossbar.
Bolton's defence, led by Jaidi, was doing well to keep Chelsea's chances to a minimum.
The problem for Bolton was that their supply line to the strike pair of Pedersen and Davies was far inferior to that of their hosts.
And matters were made worse for the vistors almost immediately after the interval when Arjen Robben's low cross found Tiago who produced a sublime sidefoot volley past Jaaskelainen's right hand.
But to their credit, Bolton did manage to reply with almost immediate effect.
Davies made the most a Jaidi flick-on that came his way to head in and reduce the deficit.
Eidur Gudjohnsen should have restored Chelsea's lead but accidently scuffed his two-yard shot.
And the striker was left to rue his miss when Sam Allardyce's men hauled themselves level.
Chelsea's Terry and William Gallas, who had defended superbly throughout the match, failed to pick up dangerman Jaidi coming in from the edge of the box.
And the Tunisian, who had been in great goalscoring form ever since arriving at the Reebok Stadium this season, made no mistake from 10 yards to send the visiting fans home happy.
Chelsea: Cech, Paulo Ferreira, Ricardo Carvalho, Terry, Gallas, Lampard, Makelele, Tiago, Duff, Gudjohnsen, Robben.
Subs Not Used: Johnson, Kezman, Bridge, Parker, Cudicini.
Goals: Duff 1, Tiago 48.
Bolton: Jaaskelainen, Hunt, N'Gotty, Jaidi, Gardner, Nolan (Campo 59), Speed, Okocha (Hierro 75), Diouf (Giannakopoulos 54), Davies, Pedersen.
Subs Not Used: Poole, Vaz Te.
Goals: Davies 52, Jaidi 87.
Ref: D Gallagher (Oxfordshire).