Turnesa is at 6-under-par 204 and one stroke ahead of second-round leader Patrick Sheehan.
The rookie had six birdies and a bogey Saturday and is looking for his first Nationwide Tour win in four career starts. The only other time Turnesa made a cut was in his first start, at the 2002 Hershey Open.
'It is nice to play well and be in contention at the first tournament of the year,' said Turnesa, who was tied for 16th overnight.
Sheehan had a 2-over 72 in his third round, dropping into second place at 5-under 205. A PGA TOUR member for the last four seasons, he is seeking his second career Nationwide Tour win (2002 Price Cutter Charity Championship).
'Tomorrow will be all about survival,' Sheehan said. 'The course is getting firmer and extremely difficult.'
Gary Christian shot his second consecutive 68 and shares third place with Ted Potter, Jr. (69) and Hunter Haas (71) at 4-under 206. Richard Johnson (66) and Tim Wilkinson (69) are two shots further back at 208.
It's the fourth straight year the Nationwide Tour has opened its season in Panama. Like the previous years, players are experiencing high temperatures and strong winds at Panama Golf Club.
Sheehan, for one, doesn't think the scores will get much better on Sunday.
'If the wind is blowing again like it did today, it will be another very difficult challenge,' he said. 'I'm thinking anything around 6 or 7 under will have a good chance.'
Indeed, even a moderately good score did wonders for players Saturday. Chris Nallen moved from 33rd place into a tie for 11th place after posting a 2-under 68.
Tough conditions knocked some other players out of it, like Andrew Johnson, who shot a 76 and plummeted from second place overnight into a tie for 11th along side Nallen.