FC Barcelona took a big step toward a berth in the Copa del Rey championship match, defeating Real Sociedad 2-0 in the first leg of their semifinal clash.

The decisive juncture of Wednesday night's match at Camp Nou occurred in the final three minutes before the intermission.

First, a breakaway opportunity by Real Sociedad was thwarted due to aggressive defending by Javier Mascherano, who prevented forward Carlos Vela from getting off a shot in the area against net minder Jose Manuel Pinto.

On the ensuing play, Barça put more than 40 minutes of missed chances behind them when Sergio Busquets slotted home a left-footed shot after a corner kick to open the scoring.

After that strike, Real Sociedad's Iñigo Martinez angrily protested the referee's decision not to award a penalty on the previous play and was sent off, leaving the underdogs shorthanded for the remainder of the contest.

Playing with only 10 men, Real Sociedad could do little more than try to avoid a blowout in the second half, and it appeared the floodgates might open after an own goal in the 60th minute.

On that play, Alexis Sanchez received a perfect pass from Cesc Fabregas and fired a strike that hit the crossbar and ricocheted to Real Sociedad midfielder Gorka Elustondo, whose attempted clear bounced off goalkeeper Eñaut Zubikarai and into the back of the net.

But the Blaugrana were ineffectual over the final half-hour, unable to increase their lead against an opponent that dug in its heels and was no longer even looking to counter-attack.

Despite the club's unimpressive performance Wednesday night at home and recent struggles that have caused it to fall out of first place in La Liga, Barça finds itself on the verge of the Copa del Rey final.

The second leg of the semifinal will be played Feb. 12 at Real Sociedad's Anoeta stadium.

Earlier Wednesday, Real Madrid took a 3-0 lead in its Copa del Rey semifinal showdown against Atletico Madrid, getting a measure of revenge for two successive defeats at the hands of its crosstown rival.

Playing at home before a crowd of more than 74,000, the Blancos dealt the Colchoneros - now leading La Liga - their first defeat in 24 matches in all competitions .

It also was the first time since January 2013 that Atleti had given up three goals in a match.

The second leg of the Real Madrid-Atletico Madrid semifinal is set for Feb. 11 at Atletico's Vicente Calderon stadium. EFE