Athletic Bilbao defensive midfielder Mikel San Jose revealed he has watched his stunning long-range goal against Barcelona "a few times" in the lead-up to Monday's second leg.

San Jose kick-started Bilbao's 4-0 win in the first leg of the Supercopa de Espana on Friday, collecting a clearing header from Barcelona goalkeeper Marc-Andre ter Stegen near the halfway line and then half-volleying into the net from inside the centre circle.

The 26-year-old's goal quickly became an internet sensation and San Jose admitted he had enjoyed a replay or two since.

"A few times. People keep sending it to me," he said at a media conference on Sunday.

"Every time someone sends me a link to the video, I'll watch it."

Asked to explain the goal, San Jose said: "As soon as the ball landed at my feet, my first thought was to shoot.

"I was just concentrating on controlling the ball so I can strike it well towards goal. I knew that the 'keeper was off his line and I had to hit the ball cleanly."

San Jose's goal was followed by a second-half hat-trick from Bilbao striker Aritz Aduriz, putting the Basque club in pole position to lift the Supercopa.

Bilbao have not won a trophy since they claimed the Supercopa in 1984 and San Jose argued silverware could have a long-lasting impact on Enrique Valverde's men.

"The trophy is within reach and we have to give everything we've got to make sure it goes home with us," he said.

"We have to play at the same level as we did the other day. Bringing the trophy back would give us an extra boost ahead of our [UEFA] Europa League play-off against Zilina and then for the start of La Liga.

"Losing it might affect us but the team is confident that won't happen."