Chelsea manager Andre Villas-Boas questioned Manchester United's second penalty as his side gave up a 3-0 lead to draw 3-3 with the champions at Stamford Bridge.
Wayne Rooney scored from the spot for the second time in the match when Danny Welbeck appeared to be tripped by Branislav Ivanovic. Javier Hernandez's late header earned United a point.
"It's difficult to take in," said Villas-Boas. "It was a massive recovery for United. We feel it's a win for them because they came back from 3-0 down. It's a disappointment for us. We had it in our hands and let it slip.
"[There were] some strange decisions today. At Old Trafford, we lost two goals to two offside decisions. These things keep happening. Today, the first one was a penalty, I do agree with that. The second one I don't think so. I don't know if Howard Webb is trying to compensate for something."
Chelsea remain fourth in the Premier League table after the draw.
