Luis Suarez scored four and Lionel Messi hit a hat-trick as Barcelona piled more misery on Gary Neville's ill-fated reign as Valencia boss to take an unassailable 7-0 lead in their Copa del Rey semi-final, first-leg on Wednesday.

Two fine finishes inside 12 minutes from Suarez put Barca in control before Messi rounded off a fine team move for Barca's third.

It could have been even worse for Valencia as Neymar hit the post from the penalty spot after Shkodran Mustafi was sent-off for bringing down Messi inside the area.

However, Messi and Suarez both added two more after the break to make next week's second-leg at the Mestalla a formality.

"It is one the best games we have played all season in every sense," Suarez told Canal Plus.

"From the first minute to the last we showed a great attitude, we were good on the ball and we have a good advantage."

The Cup had been Neville's one refuge during a winless run of eight league games since taking charge in December, but Valencia were blown away by a Barca side back to their best and on the verge of a fifth final in six seasons.

However, Neville insisted he wasn't prepared to resign just two months after taking charge.

"I won't sleep well tonight. I didn't like what I saw. The fans didn't deserve that and we have to recover incredibly quickly," said the former Manchester United captain.

"It's going to be a painful three or four days. This was one of my most painful days in football."

Neymar had made headlines earlier in the week as he was quizzed by a judge in Spain's top court over the murky transfer deal which brought him to Barca in 2013 amidst corruption and fraud allegations.

However, he showed his performances continue to be unaffected by off-field problems as he drove at the Valencia defence before playing in Suarez to fire across Australian international Matt Ryan into the far corner.

Aleix Vidal then cut-back Sergio Busquets's ball over the top of the Valencia defence for Suarez to slam home his 33rd goal of the season five minutes later.

Messi was left with the simple task of slotting in his first of the evening from close range after great work by Andres Iniesta and Suarez just before the half-hour mark.

Valencia were happy to get to the break just three down as Messi then hit the bar from Suarez's brilliant low cross before the Argentine was clipped by Mustafi as he bore down on goal.

Neymar was over-confident with his one-step run-up, though, as his penalty came back off the post.

Gerard Pique, Busquets and Messi all fired just off target as Barca continued to run riot after the break.

However, the biggest cheer of the night from the home fans was reserved for on-loan Real Madrid winger Denis Cheryshev's introduction as a substitute on his Valencia debut.

Cheryshev's inclusion when he should have been suspended saw Madrid thrown out of the competition in December.

Messi latched onto Suarez's lovely backheel to make it 4-0 and then completed his hat-trick with a fierce effort that Ryan was disappointed to see slip through his grasp.

Suarez rounded off the scoring as he powered home a header from Adriano's cross and fired in a low shot at the near post two minutes from time.