Thunderstorms and a cold wind blew across the TPC-San Antonio course Friday, forcing a delay of 3 hours, 15 minutes. There were 33 players from the 81-man field still on the course when darkness brought a stoppage of play.
Calcavecchia, wearing a heavy sweater to fight off the first blast of winter-like weather in south Texas, birdied five holes on the back nine.
Kenny Perry was alone in second at 3-under when play was stopped. He had three holes yet to play.
Tom Kite, a native Texan who has never won in the state on either the PGA or Champions Tour, shot a 2-under 70. Willie Wood, who was also at 2-under with one hole left.
This is the next-to-last event on the Champions Tour this year and Bernhard Langer has the points lead in a bid to capture a $1 million annuity at the end of the season.
Langer was 2-over with two holes to play, tied for 24th place. Defending champion Fred Couples isn't playing this week after his chronic back problems once more became an issue.