However, the day did not start well for Lee, who appealed a six-day suspension for whip use but had it dismissed as the panel agreed that he should serve a suspension that would preclude him from riding on the final two days of the season.
That decision made Dundalk's afternoon card a crucial meeting for Lee, but it was Keane who hit his stride early on when winning the Dundalk Stadium Claiming Race aboard Ger Lyons' Bucky Larson.
Keane said: "It has been a good tussle from the start to here. I'm delighted to come out the right end of it. This has been a very lucky place for us over the years.
"It probably takes the fun out of it for spectators on the weekend with Billy unfortunately missing the last couple of days.
"Billy would have been a very deserving winner and I've no doubt he could be in the same position next year. The yards he is riding for are getting bigger and stronger."
Looking back on his highlights of the year, Keane pointed to a landmark win at the Curragh in June aboard the Ralph Beckett-trained Westover in the famous silks of Juddmonte.
"It was great to ride another Classic, especially in those colours, and it was our first ever (Irish) Derby. Those are the days you work hard for.
"In January, a few of us are going travelling to Australia. I might be doing a stint in Dubai for a couple of weeks (as well)."
Of the winner, assistant trainer Shane Lyons said: "He's been a good stalwart, he's a great work horse and he's done his job.
"It is a nice winner for Colin to get him on the board for the championship."
Having arrived at the meeting tied on 89 winners apiece, Keane left with a one-winner lead as the afternoon passed with none of Lee's rides bringing him close to hitting back with a winner of his own.
The last race was a final roll of the dice but did not provide Lee with the stroke of luck he needed, forcing him to concede the battle to Keane before the Irish Flat season reaches an official end at Naas on Sunday.
Lee's ban stemmed from the winning ride on Beleaguerment at Dundalk on October 21. The stewards at the track deemed him to have used his whip with excessive frequency, but Lee regarded them to have erred in the making of that decision and lodged his appeal.
Lee's case was heard at the Curragh by Robert Dore, John Murphy and Noel McCaffrey, who heard that his use of the whip was corrective as he felt his horse shifting to the right, but after the evidence was presented the panel ultimately dismissed the appeal.
Lee is now suspended on November 4, 6, 9, 11, 16 and 18.