Messi missed Barca's pre-season tour of the United States earlier this month with a calf strain which also kept him out of the league opener against Athletic Bilbao.

The reigning champions lost that match 1-0 – their first league defeat to Athletic in six years – and though they hoped to have their all-time record goalscorer available for the visit of Betis, he was again absent from the squad announced on Saturday evening.

📋 SQUAD⚽ #BarçaBetis📍 Camp Nou pic.twitter.com/97w8oxFUkd

— FC Barcelona (@FCBarcelona) August 24, 2019

Barca coach Ernesto Valverde earlier said he will take no risks with his side's talismanic forward.

He said at a pre-match press conference: "We need to wait for training, I cannot say with any security if we can count on him.

"We cannot take a step backwards. If he's not 100 per cent, we must not risk him."

He added about Sunday's game, where defender Gerard Pique could make his 500th competitive appearance for the club: "Betis are a team who could be right up there in the table, but we're obliged to look for the three points ourselves."

🔊 Ernesto Valverde: "Gerard Piqué is an important player in the team and for the club. Playing his 500th game says a lot about his career and regularity as a historic Barça player" #BarçaBetis pic.twitter.com/Q0nbXaclJh

— FC Barcelona (@FCBarcelona) August 24, 2019

Like their hosts, Betis are also looking to get their season up and running this weekend following an agonising home defeat to Real Valladolid in their opener.

Despite being reduced to 10 men inside eight minutes following goalkeeper Joel Robles' red card, Betis still looked set to pick up a point only to concede an 89th-minute winner from Oscar Plano.

That was an unexpected setback against a Valladolid side that only just avoided relegation last season, but coach Rubi is remaining calm.

💪💚🆙

We want to see this again. Go get them.#BarçaRealBetis pic.twitter.com/V2L7zjqK8s

— Real Betis Balompié (@RealBetis_en) August 23, 2019

He said in Marca: "We've lost a game, we are on zero points, that's obvious, and there's a long way to go but all the time the players are getting closer to their potential. I'm very happy with how they are training.

"I want to see the Betis that we couldn't see the other day with 11 players. With the same level of organisation and work, with one more player, but also adventurous, with the ball and when we're pressing."

Betis can at least take a significant amount of confidence from their last trip to the Nou Camp, where they stunned the Catalan giants with a 4-3 victory nine months ago.

That is the only league defeat Barca have suffered in their last 55 home matches and was the first time an away team had scored four times at the Nou Camp in LaLiga since 2003.

🗣 @ctello91📝 His time at Barça, Barça 2019/20, #BarçaBetis and much more in this exclusive interview 👇🔵🔴 # ForçaBarçahttps://t.co/8HZ5cyuRAI

— FC Barcelona (@FCBarcelona) August 24, 2019

Former Barcelona youngster Cristian Tello was part of the Betis side that day and he believes they can cause another upset on Sunday.

He told Barca's official website: "I think we are aware that to win at Camp Nou we have to play a practically perfect match, but I think we have the team for it.

"Against Valladolid we had some bad luck, but we were very focused. Yes, I think we can win again at Camp Nou."