Heidar Helguson converted from the spot early in the first half, before both Jose Bosingwa and Didier Drogba were dismissed before the interval.
Despite praising his team for their effort, the Portuguese coach feels Foy made mistakes that changed the game.
“I have to praise the players because they were amazing,” he told Sky Sports after the defeat.
“For 45 minutes we played with nine men and that takes courage, it shows the strength and commitment of squad.
“It’s the third time in row where a referee has directly influenced the result for us and we’re not happy with this. In three games there have been blatant refereeing mistakes.
“I’m very disappointed with Chris’ performance. With nine players we kept our emotions very well. Chris and his team managed to play an emotional game and they conceded to the crowd and committed tremendous mistakes,” he concluded.
Chelsea missed the opportunity to move into second place after Manchester United’s 6-1 thumping at the hands of Manchester City, and now host Arsenal at Stamford Bridge next weekend.
By Gareth McKnight