Rain caused a nearly three-hour delay Friday and bad weather hit again Saturday with a five-hour suspension. Only a handful of players began third-round play before the round was stopped. That led organizers to cut the event to 54 holes with the final round to be completed Sunday.
Juvic Pagunsan, who had a second-round 66, is alone in fourth at 10-under.
Fernandez-Castano was on the course when rains hit Friday and had nine holes to complete in his second round Saturday. But by the time he was finished he owned the record at the Tanjong course at the Sentosa Golf Club in Singapore.
He'd opened the round with three straight birdies and added an eagle at No. 6 before another birdie at 7. He had a bogey at the eighth hole and was 5-under 31 at the turn.
In his second nine, he started with a birdie at 10, added another at 12 before back-to-back birdies at Nos. 14 and 15. He capped the round with an 18th-hole birdie.