Lionel Messi scored Barcelona's 6000th goal in LaLiga as the champions sealed a 3-0 win over Deportivo Alaves on Saturday.

The Argentina star swept in a clever free-kick midway through the second half before Philippe Coutinho netted a fine second, with Messi doubling his tally late on to secure all three points for Ernesto Valverde's side.

Alaves did little to trouble Barca's goal even after going behind, but it was far from a convincing display from the hosts, who handed league debuts to Arthur and Arturo Vidal in the second half.

Barca looked laboured despite all their possession in the first half, with creativity at a premium in Coutinho's absence, although captain Messi hit the bar with a free-kick and Ousmane Dembele fired straight at Fernando Pacheco when through one-on-one.

Coutinho was introduced at half-time for full-back Nelson Semedo, but there was little to get the 52,356 fans inside Camp Nou out of their seats until the 64th minute, when Messi sent a free-kick under the wall and into the net.

⚽ GOAL 6️⃣0️⃣0️⃣0️⃣ in @LaLigaEN: Keep them coming! 💪
🔵🔴#BarçaAlavés pic.twitter.com/gjB9uy3L7B

— FC Barcelona (@FCBarcelona) August 18, 2018

The Argentina star struck the woodwork again despite nearly slipping over in the build-up, before Luis Suarez – making his 200th appearance for the club – was denied by Pacheco when capitalising on a defensive slip.

Barca secured an opening-day win for the 10th time in succession eight minutes from time, though, when Coutinho rifled home from just inside the area, before Messi brought down Suarez's pass and slotted home with the last kick.

What does it mean: Valverde's men still in pre-season mode

This was the 10th season in a row in which Barca have won their first LaLiga match, and Messi's free-kick was certainly a fine way to mark the occasion, but there is much work to be done.

The champions were far too ponderous in possession throughout, with midfielders reluctant to run from deep and Dembele too often surrendering the ball when trying to stretch Alaves' rigid 4-5-1 set-up.

It rather felt like a friendly match, with more than 40,000 seats going unused in the stands and Barca never getting out of third gear, while the visitors made no change to their approach even after going behind.

They will improve in the coming weeks, but this was not a display to leave Real Madrid or Atletico Madrid feeling unduly concerned.

6000 - Barcelona are the second team in La Liga history to reach 6000 goals in the competition, after Real Madrid (6041 goals). Milestone. pic.twitter.com/EUdIlZ3vxy

— OptaJose (@OptaJose) August 18, 2018

Pat on the back: Messi still Barca's main man

It was fitting that Barca's 6000th goal in the top flight was scored by the man who got their 5000th back in 2009.

6000 - Barcelona's goals in La Liga:

1 - Manuel Parera 1929
1000 - Marcos Aurelio 1950
2000 - Pedro Tomás Zaballa 1964
3000 - Quini 1982
4000 - Guillermo Amor 1996
5000 - Lionel Messi 2009
6000 - LIONEL MESSI 2018

Historic. pic.twitter.com/VRfnyVstzR

— OptaJose (@OptaJose) August 18, 2018

Messi, on his first league outing as club captain and without Andres Iniesta at the club, clipped the bar in the first half before trying a different tactic to put his side ahead in the second. Some sublime close control and a deft finish added late gloss to the scoreline.

With Suarez and Dembele off the boil and Coutinho only introduced off the bench, it fell on Messi to become the main creator and goal threat for his side, and only the woodwork denied him a hat-trick.

15 - Lionel Messi is the first player in La Liga to score in 15 consecutive seasons in the 21st century (385 goals). Critical. pic.twitter.com/JYMXnU2anZ

— OptaJose (@OptaJose) August 18, 2018

6.4% - Barcelona have scored 6000 goals in La Liga history, 6.4% of them scored by Lionel Messi (384 goals). Icon. pic.twitter.com/H7DWsEECeg

— OptaJose (@OptaJose) August 18, 2018

Boot up the backside: Dembele frustrates again

Dembele looked ready for an explosive start to the season when he blasted in the winner in the Supercopa de Espana, but this was another forgettable outing at Camp Nou for the forward.

He squandered two decent first-half chances with poor finishes after failing to pick out Messi in a two-on-one situation, and his runs in the final third too often ended in possession being gifted to Alaves.

What's next?

Next up for Barca is a trip to Real Valladolid next Saturday, the promoted side having held Girona to a 0-0 draw in the first match back in LaLiga.

Alaves also play in a week's time, with Real Betis the visitors to Mendizorrotza looking to bounce back from a humbling 3-0 home loss to Levante.

FT: BARCELONA 3-0 ALAVES

Messi & Coutinho start Barça's title defence off in style! #BarçaAlaves 3-0 pic.twitter.com/LZcW4OGk6I

— LaLiga (@LaLigaEN) August 18, 2018

SECOND HALF

90+2' - GOAL BARCELONA - Messi makes it 3-0 with the final kick of the game.

🔄 85: Final change for Barça!
🔼 Arturo Vidal
🔽 Sergio Busquets#BarçaAlavés pic.twitter.com/wSP0EaPJdC

— FC Barcelona (@FCBarcelona) August 18, 2018

83' - GOAL BARCELONA - Coutinho curls one in on his favorite right foot to make it 2-0.

🔄 77: Second change for Barça
🔼 Arthur
🔽 Dembélé#BarçaAlavés pic.twitter.com/jTdfswwjid

— FC Barcelona (@FCBarcelona) August 18, 2018

70' ⏱️| 1-0

🔄 Tercer y último cambio en las filas del Glorioso

#⃣ #BarçaAlavés pic.twitter.com/E1WwxypGzW

— Deportivo Alavés (@Alaves) August 18, 2018

67' ⏱️| 1-0

🔄 Doble cambio en las filas del Glorioso

#⃣ #BarçaAlavés pic.twitter.com/vCA6ev20t8

— Deportivo Alavés (@Alaves) August 18, 2018

64' - GOAL BARCELONA - Messi sneaks a free kick under the jumping wall and tucks it into the corner to give the hosts a 1-0 lead.

48' - Jordi Alba has a close-range chance saved.

46' - Back underway at Camp Nou.

45: Change at half time for Barça
🔼 Coutinho
🔽 Semedo#BarçaAlavés pic.twitter.com/eFg70VFDY0

— FC Barcelona (@FCBarcelona) August 18, 2018

HT: Barcelona 0-0 Alaves

First Half

41' ⏱️| 0-0

🔶 Maripán ve cartulina amarilla

#⃣ #BarçaAlavés pic.twitter.com/nudGJTj4HU

— Deportivo Alavés (@Alaves) August 18, 2018

41' Suarez gets in behind but can't put it into the net.

38' Messi hits the crossbar with a free kick.

9' ⏱️| 0-0

🔶 amarilla para @danitorresrojas

#⃣ #BarçaAlavés pic.twitter.com/HknSVx6z5I

— Deportivo Alavés (@Alaves) August 18, 2018

3' - Messi gets on the end of a nice ball from Ivan Rakitic and comes close with an early chance.

1' - Underway at Camp Nou

200 - Luis Suarez will make his 200th appearance for Barcelona in all competitions (152 goals and 76 assists). Productive. pic.twitter.com/cCSFDcuxyp

— OptaJose (@OptaJose) August 18, 2018

Lineups And How To Watch

🔵🔴 Barça XI
⚽ #BarçaAlavés pic.twitter.com/Q7U6gAzbcy

— FC Barcelona (@FCBarcelona) August 18, 2018

👥 Barça subs: Cillessen, Coutinho, Arthur, Rafinha, Malcom, Lenglet and Vidal
https://t.co/pzFD9gtivE

— FC Barcelona (@FCBarcelona) August 18, 2018

#BarçaAlavés 👥 | El primer once de Abelardo en @LaLiga 2018/19 👇#GoazenGlorioso 🔵⚪🔵 pic.twitter.com/BbNzWzrPHE

— Deportivo Alavés (@Alaves) August 18, 2018

#BarçaAlavés 👥 | En el banquillo estarán 👇

Sivera (P.S), Ximo, Marín, Antonio, Burgui, Bastón y Twumasi.#GoazenGlorioso 🔵⚪🔵

— Deportivo Alavés (@Alaves) August 18, 2018

LaLiga: FC Barcelona vs. Deportivo Alaves - LIVE on beIN SPORTS and beIN SPORTS CONNECT