Chelsea were frustrated in their Women's Champions League opener as a controversial penalty call and disallowed goal helped Real Madrid draw with the Blues in Group D.
Hosts Real Madrid took the lead in the 10th minute when World Cup winner OIga Carmona's effort from range deflected wickedly off Chelsea defender Millie Bright to wrong-foot goalkeeper Ann-Katrin Berger and fly into the net.
The visitors deservedly equalised just before half-time through Niamh Charles, who was unmarked at the back post to head in Ashley Lawrence's curling cross.
Australia forward Sam Kerr completed the turnaround when she put Chelsea ahead after 75 minutes, powerfully heading home Charles' looping cross.
But two minutes later Las Blancas were awarded a penalty, with Danish referee Frida Klarlund adjudging Jessie Fleming to have fouled Athenea del Castillo in the penalty area.
Replays showed Fleming had caught her opponent outside the box but, with no video assistant referee, Carmona took the spot-kick and buried it into the top corner.
Chelsea's Lauren James struck the crossbar in the closing stages before Charles found the net with what looked like a last-gasp winner, volleying to meet a deep cross.
The goal was quickly ruled out for offside but replays showed Charles had timed her run perfectly.
Decisions disrupt Chelsea and Hayes
One trophy eludes Women's Super League champions Chelsea and departing manager Emma Hayes - the Champions League.
The club reached the semi-finals last campaign, losing to eventual champions Barcelona. Two seasons before, Barcelona beat Chelsea 4-0 in the final.
Hayes, who will leave Chelsea to take over as head coach of the US women's national team in the summer, will come away from Alfredo di Stefano Stadium wondering how her side did not start their latest European campaign with three points.
Real Madrid had two shots on target - both of them went in.
Chelsea, on the other hand, created chances at will with Kerr forcing Real keeper Misa Rodriguez into two fine saves either side of half-time and Johanna Rytting Kaneryd having a shot palmed away in the final stages.
The Blues' players and supporters will feel a sense of injustice. Fleming clearly fouled Del Castillo, but it happened a few yards outside the area with the forward's momentum meaning she fell in the box.
And replays showed Charles was the right side of Real's defensive line when Millie Bright crossed for the full-back in second-half injury time.
Instead of moving to the top of Group D, Chelsea are second after Swedish side BK Hacken beat Paris FC earlier on Thursday.
In Group C, Bayern Munich drew 2-2 with Roma and Ajax beat two-time finalists Paris St-Germain 2-0.