Barca seemed all but out of the title race after conceding a last-minute equaliser to draw 2-2 at home to relegation-threatened Getafe last weekend.
However, leaders Atletico Madrid subsequently lost 2-0 away at Levante leaving Barcelona only three points adrift.
But Barcelona can win the league if they win their two remaining games away to Elche on Sunday and then when Atletico visit the Camp Nou on the final weekend of the season.
"We are in a better position today than we were a few weeks ago," said Messi.
"We can see that we have an opportunity to win the league. We need to take advantage of this moment and not let it escape."
Gerardo Martino's men are sure to face a tough task this weekend, though, as Elche are in need of points themselves as they sit just three points above the relegation zone and have yet to be beaten at home in nine league games so far in 2014.
Barca will again be without the injured Gerard Pique, Jordi Alba and Neymar, although all three are hopeful of being fit for the potential title decider against Atletico next weekend.
However, should Barca fail to win this weekend, Atletico can mathematically seal their first title in 18 years with victory over Malaga at the Vicente Calderon.
Atletico have injury worries themselves as top scorer Diego Costa looks set to miss out due to a hamstring injury, which could yet endanger his participation in the clash with Barcelona and in the Champions League final against Real Madrid on May 24.
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