Chelsea suffered a fifth defeat of the season after losing 2-1 to Porto in the UEFA Champions League on Tuesday night.
The home side led just before half-time through Andre Andre's close-range finish, only for Willian's brilliant free kick to draw the Blues level with the last kick of the first half.
However, Porto took the spoils thanks to Maicon's near-post header seven minutes after the break, although the visitors were denied a clear-cut penalty in the final minute of the game.
Chelsea head coach Jose Mourinho had said in the build-up to the game that none of his players were "untouchable", and the Portuguese proved true to his word when his starting line-up was announced.
The Premier League champions left captain John Terry, playmaker Eden Hazard (who was introduced just past the hour-mark) and holding midfielder Nemanja Matic all on the bench, while the likes of Radamel Falcao, Loic Remy and Oscar did not even travel to Portugal.
If Mourinho's changes were meant to spur his players into life in the early stages of the game, then the 'Special One' will have been pleased as the Blues created two good openings in the opening quarter of an hour, only for veteran Porto goalkeeper Iker Casillas - making a record 152nd Champions League appearance - to deny them on each occasion.
Midfield creator-in-chief Cesc Fabregas had the first chance after just six minutes, however, the former Real Madrid shot stopper got down well at his near post to push his compatriot's fiercely struck struck shot behind for a corner.
Minutes later Chelsea really should have broken the deadlock following a lovely move involving Diego Costa, whose neat cushioned header on the halfway line released the rampaging Willian, and he then slipped Pedro clean through on goal, only for the forward's low shot to be easily saved by Casillas.
And Chelsea were made to pay for that miss when Porto took the lead six minutes before half-time after a brilliant driving run by their lively left-winger Yacine Brahimi, who easily beat Branislav Ivanovic - having another one of those games for the Blues - before unleashing a well-struck shot that Asmir Begovic did well to get a hand to.
However, unfortunately for Chelsea's stand-in 'keeper, the ball fell straight at the feet of midfielder Andre, with the Portugal international having no problems tapping the ball home from six yards out to send the home fans into a state of delirium.
But if Porto boss Julen Lopetegui thought his side would go in leading at the break, he was mistaken as Chelsea drew level in first-half stoppage time after Ramires's powerful run was halted close to the Porto penalty area.
And from the resulting free kick, Willian beat a motionless Casillas with the last action of the half on the Brazilian's 100th appearance for Chelsea, but the visitors were not level for long though as Porto soon retook the lead after half-time.
Again the Chelsea defence was at fault as Ramires was caught napping at a corner, allowing Porto centre-back Maicon the room to steer a header past Begovic at his near post.
The visitors could have almost immediately drawn level, only for Costa's lovely curling effort from the left-hand corner of the box to beat Casillas, but not the bar.
Thereafter, though, it was Porto who looked the most likely to score again, and they would have done but for a series of impressive saves by the outstanding Begovic, with the Bosnian in particular doing well to deny Giannelli Imbula with one reflex stop 20 minutes from time.
However, there was nothing the Chelsea 'keeper could do when Danilo headed substitute Miguel Layun's right-wing corner against the post with nine minutes remaining as the Portuguese went in search of a third goal.
And Porto would have needed it had Spanish referee Antonio Miguel Mateu Lahoz spotted a blatant handball by defender Ivan Marcano in the final minute of the game as the Porto defender stopped Costa's pass with his hand in the box.
A draw, though, would have been harsh on Porto, who thoroughly deserved the win that keeps them joint top of Group G, while Chelsea - in third place in the standings - have now lost more games in all competitions than in the whole of the previous campaign.