GAA history will be made tonight when 13 senior inter-county football teams play under lights in a nine-game midweek programme for the first time.
They will be joined by five third-level colleges to complete the busy line-up. With the exception of Kilkenny, who are not competing, all the Leinster counties have O'Byrne Cup action, while Fermanagh take on Donegal in the Dr McKenna Cup in Enniskillen.
Donegal will play a largely reserve squad as the panel that won the All-Ireland title have only returned from holiday in Dubai.
Counties and colleges face a third game in the final round of group ties on Sunday with the top four in each section advancing to the semi-finals.
While managers are using the blitz to assess as many players as possible, there is some disquiet over playing three games in a week. Dublin manager Jim Gavin described the programme as "a bit much" after the win over Carlow last Sunday.
With counties returning to training on a staggered basis, depending on the point of their championship exit last year, there are some concerns that such a concentrated programme increases the risk of injury.
This is the first time that the O'Byrne Cup has been played on a round-robin basis, involving a midweek programme, so officials will be keeping an eye on attendances tonight after good turn-outs at most of last Sunday's games. Leinster have worked at promoting the O'Byrne Cup, sponsored by Bord na Mona, in order to maximise financial returns for a special fund to alleviate recessionary hardship among players, mentors and their families.