LAS VEGAS (AP) _ Don Helling apparently likes bowling in Las Vegas. The question is whether his bowling thumb can stand up to the dry and hot conditions.

Helling, from St. Charles, Mo., was running second in the U.S. Open last month when his thumb began to swell.

``It hurt,'' Helling said. ``I don't know if I panicked or what, but I sure bowled poorly after that.''

Helling, winner of four tournaments on the PBA tour and another as a senior, set aside worries about his thumb to take the third-round lead Wednesday in the $150,000 Showboat PBA Senior Invitational.

Helling, second after Tuesday's round, averaged 227 in building a 29-pin lead over John Hricsina of Franklin, Pa..

Hricsina, with 5,423 pins, had a 95-pin edge on third-place Vince Range of St. Louis, with Don Johnson of Las Vegas another 12 back in fourth. Dick Baker of Libertyville, Ill., rounded out the top five with 5,309.

The leaders bowl two eight-game blocks Thursday and Friday before the top five advance to Saturday's finals.