Williams needed a strike in his first ball of the 10th frame to lock up a championship in the PBA50 South Shore Open Thursday at Olympia Lanes.
But he left the 10 pin and the most decorated bowler in PBA history (Williams Jr., no relation) earned yet another victory.
"I appreciate Mark giving me a break," Williams Jr. said. "He was nice to me the other day on the golf course and now today bowling again."
The final score was 217-198. Splits in the fourth and and fifth frames kept Williams from burying Williams Jr. early in the match.
"It was great bowling with Mark this week and I know we'll be battling again next week," Williams Jr. said. "Hopefully, we'll be (at Olympia Lanes) again next year."
The final eight was a who's who of the bowling world.
Williams, Jr. and Pete Weber are two of the most decorated bowlers in history. Randy Pedersen is ESPN's bowling commentator. Mark Williams has two career wins at Olympia Lanes alone.
Even the lowest qualifier to reach the level was a big name; Dave Bernhardt is the founder of bowling equipment company Turbo.
All four bowlers in the final four -- Williams Jr., Williams, Pedersen and Weber -- were hall of famers.
Weber came into the day as the top qualifier, besting the field by an astounding 414 pins. But he guttered his first throw in the semifinals and left splits in the third and sixth frames, leading to a 267-191 loss to Mark Williams.
"I know (Weber) struggled a little bit in the semifinal match but he bowled unbelievable in qualifying," Williams Jr. said. "My hat's off to him."
Williams Jr. topped Pedersen 244-199 in the other semifinal match.