Champions Real Madrid lie eight points back in fourth place after Gonzalo Higuain and Cristiano Ronaldo both scored a brace in Palma to secure a 5-0 victory over Real Mallorca.
In-form Colombia striker Falcao pulled away from his marker and volleyed Atletico's third high into the net after 73 minutes, sealing an eighth straight league victory for Diego Simeone's side.
Atletico are second with 25 points from nine games, behind Barca on goal difference, after Tito Vilanova's side thrashed Rayo Vallecano 5-0 away on Saturday when a double from Lionel Messi helped him reach 301 senior career goals.
Osasuna pulled one back just before half-time but Atletico always looked more dangerous and Falcao lashed home Juanfran's cross to score in his 11th consecutive match for club and country.
"When it is near the end of the season that will be the time to see where we are in the table," Atletico defender Miranda told reporters.
"Then we'll know if we have a chance for the title or if we can make it into the Champions League."
Argentina striker Higuain made the most of a defensive error to volley Real in front after only seven minutes and as Jose Mourinho's side pressured the hosts into further mistakes Higuain laid the ball off for Ronaldo to grab the second.
Substitute Jose Callejon grabbed Real's fifth at the end.
Martins created both his goals by robbing the ball off defenders and helped maintain Levante's unbeaten home record.
Marcelo Bielsa's Athletic Bilbao are still struggling to get anywhere near the heights they hit last season, when they reached the King's Cup and Europa League finals, as they slumped 2-1 at home to Getafe.
