Lionel Messi on fire as Barcelona thrash Alaves

Victory means Barcelona trail league leaders Atletico Madrid by eight points

Barcelona's Lionel Messi (No.10) challenges Alaves' defender Florian Lejeune (No.22) and goalkeeper Fernando Pacheco. AFP

Barcelona might not be able to catch Atletico Madrid but they may fancy their chances against Paris Saint-Germain after Lionel Messi scored twice in a 5-1 thrashing of Alaves on Saturday.

Messi fired in two sensational long-range efforts and would have had a hat-trick at Camp Nou had a dubious VAR decision in the first half not ruled Antoine Griezmann offside.

He did tee up a second of the night for the 21-year-old Francisco Trincao and was instrumental in Junior Firpo adding a fifth too, a flamboyant scoop freeing Griezmann to send a pass to Firpo at the back post.

"Leo is focused, he's happy, he's ruthless. When we play those passes through the lines to him and he finds those gaps, everything is easier," said Ronald Koeman.

Victory means Barca trail Atletico by eight points again after the leaders temporarily pulled 11 clear thanks to a hard-fought 2-1 win over Granada earlier on Saturday.

Barcelona's Champions League tie against PSG, which had the French side as firm favourites when the draw was made in December, now feels harder to call.

The question is whether a free-flowing Barca attack – full of talent and orchestrated by Messi – can hurt PSG enough to make up for what remains a shaky defence, depleted by injuries and vulnerable to the counter-attack.

"We're in good form," said Koeman. "We keep creating chances and improving in all aspects of our game. PSG are a great team but I see the tie as very balanced. We go into it with confidence, knowing we need to be at our best to go through.

With Gerard Pique and the emerging Ronald Araujo both out injured, Frenkie de Jong filled in again in central defence, although the Dutchman has arguably been Barcelona's most improved player this year in the midfield three.

Instead there was a start for Ilaix Kourouma in midfield, the 18-year-old academy product who assisted Trincao's opening goal but whose misplaced pass led to Luis Rioja briefly giving Alaves hope.

After Trincao had swept home, Messi thought he had made it two, pouncing on a rebound after Griezmann missed but the goal was ruled out, even though replays suggested Griezmann was onside.

Messi scores Barcelona's second goal. Reuters

Messi made amends soon after, latching on to a Sergio Busquets pass, darting in-field and ripping a shot in off the post.

Rioja capitalised on Ilaix's mistake just before the hour but Barca pulled away with three goals in six minutes.

Pedri's pass freed Messi but he failed to round Fernando Pacheco and instead the ball spilt out for Trincao to score his second.

Messi slammed a stinging strike into the top corner from 25 yards to make it 4-1 before perhaps the goal of the night came last, Messi scooping over for Griezmann, who volleyed to the back post where Firpo could not miss.