Having to steer two of the day's biggest outsiders and the scratching of one of his five drives resulted in the Oamaru reinsman slipping from third to fifth on the leader board at the end of the Sundbyholm meeting.
Williamson finished the day on a positive note with a second and a fourth.
The reinsman took matters into his own hands to secure vital points, when Lass Revenue ran second in the final heat of the day.
Williamson had the trotter in front from barrier 2 and refused to hand up the lead early.
He then took a trail at the halfway mark, while a three-way duel for the lead played out.
Lass Revenue rallied well in the straight to get within half a length of winner My Dream Art and Norwegian driver Eirik Hoitomt.
Williamson was unlucky not to pick up more points behind the fourth-placed Idreamicanfly.
He worked the trotter into the trail and the horse was full of running in the home straight.
Idreamicanfly finished hard on the back of the winner Argbiggan and leading driver in the series, Doug McNair, of Canada.
''The horse was very unlucky, but I was happy to be up on the speed and running fifth,'' Williamson said.
''Lass Revenue went a good race in the second heat.
''She got close, but just couldn't get to the winner.
''The series is going pretty well.
'' I just need to get on some good horses in the next two rounds.''
Williamson still has a chance to win the championship, as there are still 10 races remaining.
Five of those were to be contested at the Rattvik this morning.
