Messi scored twice and created goals for Arturo Vidal and Luis Suarez as champions Barca moved top of the table with 22 points from 10 matches.
Barcelona, who are struggling for goals, host Olympique Lyon in Wednesday's Champions League opener in Group E.
Valencia's drive to rejoin the title race gathered momentum when they swept aside Real Mallorca 3-1 in the Primera Liga on Tuesday.
Real Madrid crushed Athletic Bilbao 3-0 at the Bernabeu on Sunday to edge closer to the Spanish title but Villarreal's 1-0 victory at Real Betis put their celebrations on hold for at least another week. Real's victory means that with four games left to play they remain 10 points clear of Villarreal at the top of the table on 75 points and will claim their 31st league title if they win next week's match at Osasuna.
King's Cup holders Barcelona have a fight on their hands if they are to remain in the competition after losing a fiery first leg of their last-16 tie at Athletic Club 2-1 on Thursday despite playing the final 10 minutes with a two-man advantage. Spain striker Aritz Aduriz headed Bilbao in front in the 25th minute and the veteran produced an audacious flick to tee up youngster Inaki Williams to volley in the second three minutes later. Talisman Lionel Messi pulled a full-strength Barca side back into the game with a free-kick in the 52nd minute which came off the underside of the bar and over the line.
Athletic Bilbao have proudly resisted pressure to abandon their policy of only recruiting players of Basque origin, making it all the more impressive that they are the club standing between Barcelona and a record-extending 27th King's Cup.
Barcelona reached the semi-finals of the King's Cup after a Thierry Henry earned them a 1-0 victory over 10-man Villarreal.
Real Madrid took full advantage of slip-ups from the chasing pack by beating Villarreal 3-2 to move nine points clear in the Spanish Primera Liga.
It is not the first time the midfielder has received a reprieve after initially being banned for picking up a fifth yellow card.
The English champions have agreed to sell defender Asier del Horno to Valencia.\n
Lionel Messi struck late to help Barcelona seal a place in the King's Cup final on Wednesday, a 1-1 draw at Real Mallorca completing a 3-1 aggregate victory for the Primera Liga leaders. Barcelona will play Athletic Bilbao in the May 13 final in Valencia after the Basque club beat Sevilla 3-0 at home to overturn a 2-1 defeat from last month's first leg.
Real Madrid charged seven points clear at the top of the Primera Liga after a 1-0 win at Athletic Bilbao.
Federico Valverde finished off a stunning move in extra time to give Real Madrid a 3-2 victory over arch-rivals Barcelona
Barcelona travel to newly-promoted Osasuna without their first choice front line.
Antoine Griezmann headed two goals for Atletico Madrid in a 3-1 victory over Levante that kept them on the heels of La Liga leaders Real Madrid on Saturday.
Alvaro Negredo struck in stoppage-time as stuttering Valencia won 2-1 against his former club Sevilla on Sunday to earn coach Pako Ayesteran victory in his first home game in charge since succeeding Gary Neville.
Barcelona's march towards the Primera Liga title slowed on Saturday after a goalless draw with bottom-placed side Malaga.
Goals from Ronaldo and Roberto Carlos moved Real Madrid up to second in the Primera Liga on Sunday.
Barcelona coach Luis Enrique allowed himself a brief moment to savour Saturday's King's Cup triumph over Athletic Bilbao.
A roundup of weekend action in the main European leagues.\n
The Real Madrid striker will miss the club's King's Cup match against Athletic Bilbao
Ronaldo returned from his lavish Valentine's Day engagement party in Paris with an injury to his toe.
Atletico Madrid kept pace with leaders Barcelona and restored their five-point lead over third-placed city rivals Real when Diego Costa and David Villa each scored a penalty in a 2-1 win at Granada in La Liga on Thursday.
Leaders Barcelona and Real Madrid were held to draws while Sevilla made up ground on the top two and Alaves slipped after a promising start. Here are five talking points from the weekend's La Liga action.
Barcelona striker Samuel Eto'o finished with 26 goals as he scored in his side's 3-1 defeat at Athletic Bilbao.
The Premier League champions signed Athletic Bilbao left back Asier del Horno for $14.50 million on a three-year contract.
Real Madrid chalked up their fifth Primera league victory in a row with a 2-0 win at Athletic Bilbao.
Real Madrid were dumped out of the Copa del Rey at the quarter-final stage on Thursday after losing 4-3 at home to Real Sociedad, while record 30-times winners Barcelona were sent crashing out of the Copa del Rey in a 1-0 defeat at Athletic Bilbao.
Lionel Messi was at the top of his game as Barcelona earned a 3-2 win at Athletic Bilbao on Wednesday to move up to third in La Liga.
10-man Real Madrid fought back from a goal down to claim a 3-1 win at home to Athletic Bilbao.
Barcelona coach Luis Enrique has decided to rest Lionel Messi, Neymar and most of his regulars for the King's Cup last 16, second leg match at Elche later on Thursday.
La Liga leaders Barcelona were held to a 2-2 home draw by Celta Vigo on Saturday as their former assistant coach Juan Carlos Unzue dented the title hopes of the Catalans, who dropped points for the second game in a row for the first time this campaign.
Barca lead the standings on 39 points from 18 games, three clear of second-placed Real Madrid who host Athletic Bilbao on Sunday.