Pedro scored on his debut as Chelsea won for the first time this season - 3-2 at West Brom - despite a red card for John Terry.
Pedro - who also provided an assist for Diego Costa - gave the visitors the lead on 20 minutes after James Morrison's early penalty had been saved by Thibaut Courtois.
Costa doubled Chelsea's lead 10 minutes later before Morrison made amends for his earlier miss, making it 2-1 on 35 - only for Cesar Azpilicueta to restore the Blues' two-goal lead three minutes before the break.
Chelsea looked to be in command until Terry was sent off for bringing down Salomon Rondon on the edge of the box on 54 minutes, before Morrison scored again five minutes later to cause Jose Mourinho - who spent the final minutes crouched pensively on the touchline - some late nerves.
However, Chelsea managed to hold on to record their first win of the season, but this encounter provided further evidence that retaining their title, even with Pedro firing on all cylinders, will be anything but easy.
Pedro started for the Blues just days after joining from Barcelona, with Saido Berahino left out of the matchday squad for West Brom amid speculation he could be about to sign for Tottenham.
Costa, who looked back to his menacing self, could have opened the scoring after just six minutes, but he dragged wide from a good position.
Just five minutes later however, Morrison had a fantastic opportunity to break the deadlock from the penalty spot, after Nemanja Matic had brought down Callum McManaman in the box.
Not normally the penalty taker, Morrison took the ball from Chris Brunt and hit it hard down the middle of the goal, but saw his attempt saved by the legs of Thibaut Courtois, back in the Chelsea side after suspension.
The Baggies were made to pay minutes later with new-boy Pedro making an immediate impact on his debut.
The Spain forward carried the ball towards the edge of the box, cut inside, before firing past Boaz Myhill, via a slight deflection, to give the visitors the lead.
Pedro then turned provider for Costa, firing across goal for the striker to divert home to put the Blues in command.
Tony Pulis' side eventually got a reward for their endeavours on 35 minutes, with Morrison drilling the ball home after debutant Rondon had brilliantly kept a deep cross alive.
However, Chelsea quickly restored their two-goal lead, with Azpilicueta latching onto a loose ball after Costa had chested a lofted centre down, to score his first goal for the club.
After the interval, Chelsea seemed comfortable until Terry was adjudged to be the last man and was given his marching orders.
The Blues skipper was struggling to keep pace with the energetic Rondon, and tugged the Baggies' record signing back before he could reach the box, and was handed a straight red.
The hosts grew in confidence as a result, and closed the gap just before the hour mark, with Morrison again getting on the scoresheet, this time with his head, converting a pinpoint McManaman cross.
Costa almost made the result safe following more brilliant work from Pedro, but he fired just wide with Myhill beaten.
McManaman curled just past the post before a frantic final 15 minutes saw both sides have chances to score, but the Blues held on for a vital three points, and showed some much-needed resilience to silence some of the doubters.
Player ratings
West Brom: Myhill (6), Dawson (6), McAuley (5), Olsson (5), Brunt (6), Morrison (8), Fletcher (7), Yacob (6), McClean (7), McManaman (8), Rondon (7).
Subs: Gnabry (7), Gardner (6), Lambert (5)
Chelsea: Courtois (7), Ivanovic (5), Zouma (6), Terry (5), Azpilicueta (7), Matic (6), Fabregas (7) Pedro (9), Willian (5), Hazard (7), Diego Costa (8).
Subs: Cahill (6), Falcao (5), Mikel (5).
Man of the Match: Pedro (Chelsea)