Star forward says he had never met his fellow Argentine although he had heard about managerial record.
Lionel Messi denies influence in Martino decision at Barcelona
Martino said in a news conference on Tuesday night that he was sure fellow Argentine Messi and his father Jorge had put in a good word for him with the Barcelona hierarchy before the Catalan giants offered him the job.
However, the four-time Ballon d'Or winner has said he had no influence in Barca's decision.
"I have nothing to do with Martino's signing nor do I have to give any explanations. It was down to president [Sandro] Rosell and the club. I said before that he seemed a good coach, but I don't have to explain anything," he was quoted as saying by AS following Barca's friendly defeat to Bayern Munich.
"I don't know him personally, I've never met him. Not him nor Luis Enrique, the other one they've been talking about.
"I think he's a good signing, he showed at Newell's and with Paraguay what he's capable of. Hopefully he'll be good for us."
Martino, who led Newell's Old Boys to the Argentine Clausura title last season and guided Paraguay to the quarter-finals of the 2010 World Cup and final of the 2011 Copa America, has agreed a two-year contract with Barca and will be presented on Friday at lunchtime.
The 50 year old replaces Tito Vilanova, who stepped down from the post last Friday as he continues his battle with cancer.
Messi sat out Barca's final three games of last season with a hamstring problem but he started the club's opening pre-season friendly against Bayern before being replaced at half-time.
"Luckily, my injury is now behind me," he said. "I'm completely recovered and I'm really looking forward to the new season."
Regarding the change in coach, the Argentina ace added on his club's website: "We're very sorry for what has happened but the team is strong. We have to keep on moving forward."
Even with Messi in the starting line-up, Barca were unable to gain a measure of revenge against Bayern for the 7-0 aggregate mauling they suffered at the hands of the German giants in last season's Uefa Champions League semi-finals.
Treble-winners Bayern, now under the leadership of Pep Guardiola, the former Barca manager, won the friendly 2-0 at the Allianz Arena with Philipp Lahm opening the scoring in the 14th minute and Mario Mandzukic adding a second three minutes from time.
Jose Pinto, the Barca goalkeeper whose side were missing their Spain internationals and summer signing Neymar, said: "It was the first match of the pre-season. We didn't get a good result but what's important is that the match will help us improve and get in shape."
"It was a complicated match," the defender Marc Bartra added. "Bayern are on better form than we are and it was obvious."
Jordi Roura, who took over the reins last season when Vilanova was undergoing treatment for his cancer in the United States, and recently-appointed assistant Rubi have taken charge of Barca on an interim basis ahead of Martino's arrival.
The former Paraguay coach is due to be officially unveiled by Barca on Friday and Bartra, 22, is hoping to impress the new manager.
"I'm very eager to start working with Martino," he said.
"I have to keep on giving 100 per cent and try to win my spot in the starting line-up regardless of who the manager is."
Alexis Sanchez, Barca's Chilean winger, added of Martino: "I'm looking forward to meeting him. He's very highly thought of in Chile.
"I'm also looking forward to playing with Neymar, Messi, [Andres] Iniesta...with everyone. It's a great team!"
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