MADRID, Spain -- Barcelona says forward Lionel Messi has re-injured a right hamstring that has limited his playing time during the past six weeks.
Messi aggravated the hamstring he originally hurt on April 2 in Sunday's 2-1 win at Atletico Madrid.
The Argentina forward will undergo tests on Monday.
Messi, who was making his first league start since the injury, left the pitch in the 68th minute after Barcelona had made all three substitutions and was trailing 1-0.
His side rallied with two goals to win the match the day after Barcelona had clinched the league title through Real Madrid's draw.
Barcelona coach Tito Vilanova says Messi "was feeling good but the pain can come back immediately."