Buffon, Italy's first choice ’keeper, was replaced at half time after aggravating a back twinge he felt earlier during the warm-up in the rain where temperatures averaged about 8 degrees celcius.
"He had a bit of a problem in his back. He had a back ache during the warm-up -- already it started to manifest itself," Lippi said after the match. "The doctors will have to say (if he'll be back for the next game)."
The Juventus goalkeeper, rated one of the best in the world, was replaced by Frederico Marchetti at half time with Paraguay leading 1-0 thanks to a headed goal by Antolin Alcaraz.
Buffon, it was announced later, would be out of action for an indefinite period. “He has a bad sciatic problem. We cannot say when he will be able to play again,” said an Italian Football Federation statement.
Lippi's side laboured, with key creative midfielder Andrea Pirlo absent through injury and only expected to return for the third group game. Despite a shot-shy performance and lack of penetration, the coach was pleased with his team's display.
"I'm very satisfied with our performance. I'm very statisfied with the approach to the world cup ... our opponent was described as being a very fierce opponent, so I'm very happy," he said.
He said Italy had created the most opportunities in the game while denying Paraguay any clear cut chances in the second half. "The only thing I regret is normally matches of this type we win," he said.