The record books were rewritten at the 33rd Callaway Golf PGA Assistant Championship, as Tim Thelen of New Ulm, Texas, fired a final round 4-under-par 68 for a 265 total.
PGA apprentice Sean Dougherty of Overland Park, Kan., finished in second place.
Thelen broke the 72-hole Championship scoring record of 270, which was previously held by Kyle Finton of Edmond, Okla., by five strokes. Finton set the mark in 2003.
Thelen also came within a stroke of the largest margin of victory record, winning by seven strokes. That record of eight strokes was also set by Kyle Flinton, who set the mark in 2005.
"I got off to a hot start again today with birdies on the first two holes," said Thelen, who also broke the 36-hole and 54-hole scoring records. "After I got off to a good start I just coasted in and didn't make any big mistakes."
The 48-year-old PGA assistant professional at The Falls Golf & Country Club in New Ulm, Texas, admitted that this year's Championship produced some of his best tournament play ever.
"I really don't think I could have scored any better then I did," said Thelen, who also owns two PGA Professional National Championship titles. "I made four bogeys all week and on this golf course it's hard to do because there is trouble lurking everywhere."
Thelen, who was one of the oldest players in the Championship, was able to stick to his game plan despite not being able to hit the ball as far as many of the younger players.
"I got a couple more years before I move up a tee box," said Thelen. "These guys are bombing it by me but I stick to my plan of hitting greens and making putts. This victory is very gratifying."
Thelen, who collected $9,000 for his victory, will attempt to win his third PGA Professional National Championship at the 43rd PGA Professional National Championship, June 27-30, 2010, at French Lick (Ind.) Resort.
Dougherty, the runner-up who is a PGA apprentice at Milburn Country Club in Overland Park, Kan., was extremely pleased with his play.
"I played well but Tim [Thelen] played better," said Dougherty. "I enjoyed being able to play with him today. He is one great player."
Dougherty, who shot a final round 68, will look to build on his confidence in the near future.
"I can take all of this confidence in my game into next year and future events," said Dougherty, who was competing in his second PGA Assistant Championship."My play this week was as good as any tournament I have ever played in at all. I kept my emotions in check all week and played solid golf with no real hiccups."
Martin Maritz of Broken Arrow, Okla., fired a sparkling final round 66 to grab third place overall.
The victory marked Thelen's third national title (he won the 2000 and 2003 PGA Professional Championships), and the first national title for a Southern Texas PGA member since Brad Lardon won the 2006 Callaway Golf Assistant Championship.
It was also the fourth time a Southern Texas PGA member has won the assistant's title. In addition to Thelen and Lardon, Wes Short won the tournament in 1994 and Robert Thompson topped the 1986 field.
Ryan Polzin, an assistant professional at Houston's Royal Oaks Country Club and the winner of the 2009 Callaway Golf STPGA Assistant Championship, posted a total of 66-73-70-70 - 279 which was good enough for an 8th place tie and $2,025 in winnings. Casey Carnes, an apprentice assistant professional at Woodlake Golf Club in San Antonio, finished at 70-71-71-71 - 283, winning $828.33 for his 27th-place tie.