Barcelona coach Luis Enrique says that Lionel Messi's penalty issues do not make the Blaugrana superstar seem any less of a visitor from another planet.

Messi scored twice in Sunday evening's 4-1 La Liga win at home to Levante -- one an expertly dispatched penalty -- and set up another as Barca continued their 100 percent start to the new La Liga season to remain two points clear in the table.

But the Argentine's evening was marred by him skying a second penalty kick over the bar soon after he had scored his first -- and the 28-year-old has now missed six of the 44 La Liga spot kicks taken in the decade he's spent in a Barca shirt.

Asked at his post-game news conference if this penalty issue actually made the otherwise otherworldly Messi seem human, the blaugrana coach pointed to how the No 10's overall contribution to the game had been well above the other mere mortals on the pitch.

"To miss penalties does not make Messi human," Luis Enrique said. "Then he scores two goals and gives an assist. There is very little human about Messi."

The Asturian did admit that a much-changed Barca XI -- who have gone to the break at 0-0 in all four La Liga games so far -- had found it difficult to break down a stubborn Levante defence during the first half.

"It took some effort, but I am happy with the game and to see that we are a squad with various options," Luis Enrique said. "It is important to score as quickly as possible to break open defensive set-ups. Tiredness also helps to unblock them."

With versatile youngster Rafinha injured, and Andres Iniesta and Luis Suarez rested, Barca started with an attacking lineup containing just Sergio Busquets and Ivan Rakitic as conventional midfielders.

Luis Enrique said the system, which featured Messi in a floating No. 10 role, was another option when Barca faced teams who packed in their defence.

"To change the system is an option we have, and we tried it as we knew Levante would play with five defenders," he said. "To be able to change the system, and for opponents not to know how we'll play, is good. In 22 days we will play seven games, we have already played three or four of them, and the players need to rest and for playing time to be shared."

20-year-olds Sandro Ramirez and Munir El-Haddadi both played all 90 minutes, without really impressing neutral observers, but Luis Enrique said he was happy with the ex-La Masia pair's contributions.

Barcelona players celebrate after scoring a goal. File Photo: AFP

"I liked how Sandro and Munir did," he said. "They are youngsters, goalscorers, and will keep getting playing time to do their bit. We all expect them to score two or three a game, but that is difficult."

There were also positive words for goalkeeper Marc-Andre Ter Stegen, who was at fault for Levante's goal, after also being caught out during the midweek Champions League 1-1 at Roma.

"If it were another goalkeeper he might lose confidence in himself," Luis Enrique said. "But not Ter Stegen, confidence flows through his body. He will come out again, and continue to play with personality and character. He's been unlucky, but is a true Barca keeper."

Next up for Barca is Wednesday's trip to unbeaten Celta Vigo, who have 10 points from their first four games after winning 2-1 at Sevilla on Sunday, and Luis Enrique said he expected an entertaining game back at his former club.

"Celta are one of the most entertaining teams to watch in Europe," he said. "They have an attacking mentality, they go on the attack. I heard their first half at Sevilla was spectacular."