Eastwood, 83, noticed a "look of panic" on the face of tournament official Steve John as he tried to swallow a piece of cheese during a function for tournament volunteers at the Monterey Conference Center in California.
Immediately, Eastwood stepped in and performed the Heimlich manoeuvre. "I looked in his eyes and saw that look of panic people have when they see their life passing before their eyes," Eastwood told a local newspaper. "It looked bad.
"The look on Steve's face was different than when somebody is just coughing or joking around. I gave him three good jolts and that got it out. And then I made him drink a big glass of water with a bunch of lemon squeezed in it."
Eastwood, a prominent figure at the Pebble Beach National Pro-Am where he used to compete as an amateur, said it was the first time he had used the Heimlich manoeuvre.
"We were just talking," John said. "A piece of cheese went in my mouth, and suddenly I couldn't breathe. It was as bad as it could have been. Clint came up behind me, and he knew exactly what to do. He lifted me right off the ground. He's strong! The cheese popped out, and I was fine. Clint saved my life."
Eastwood performs an official role at the tournament as chairman of the Monterey Peninsula Foundation and presents the trophy to the winner tomorrow. Previous recipients include Tiger Woods and Phil Mickelson.
Leading overnight was the rookie Andrew Loupe who shot a first-round 63 before the heavens opened. The 23-year-old Americ, who has not made the cut on his five Tour appearances to date carded an eight-under round to open a two-shot lead.
Loupe was faultless in not dropping a shot and holds an advantage over a chasing pack of five, made up of Stuart Appleby, Jimmy Walker, Jim Renner, Scott Gardiner and Richard H Lee.
Forty players were left with incomplete first rounds after a three-hour rain delay which eventually turned into bad light, with three-time winner Phil Mickelson among them. He is well placed on five under after 15 holes.
Also on that score is the European Ryder Cup captain, Paul McGinley, making a rare appearance on American soil. He completed his round. Graeme McDowell was one under and Padraig Harrington level after disappointing displays.