GAS romped to the finals after surmounting a tough challenge to beat Shauri Moyo United 3-2 in the Nairobi East region finals.
In the Nairobi West regional finals, Kawasaki booked their place in the grand finale for the second year in a row after edging out South C Rangers 1-0 courtesy of a lone strike from Ali 'Aguero' Maleche.
They advanced to the semifinals after defeating Asec Huruma 4-3 on post-match penalties after a fierce battle.
Githurai captain Kevin Njuguna converted a penalty in the fourth minute, but Abednego Wawire equalised in the 16th minute with a stunning strike. Nganga Edwin restored Githurai's lead in the 30th minute, but Wawire cancelled it again in the 42nd minute.
In the 56th minute, Nganga made the difference by scoring a close-range goal to give the reigning champion the victory.
The two sides will renew their rivalry following last year's finals, where GAS pipped Kawasaki 5-4 on post-match penalties at the Police Sacco Stadium to storm to the inaugural title and bag the Sh3,000,000 cash prize.
Kawasaki only needed a goal from Ali "Aguero" Maleche to defeat South C Rangers and earn a spot in the finals against GAS.
Meanwhile, South C Queens will battle Shrink Pack Ladies FC in the women's finals at Dandora Stadium on Friday. The Queens crushed the Nairobi Starlets 3-1 in an entertaining Nairobi West region final.
Maureen Omekede put Queens ahead in the first minute of the match before Mercy Baraza restored parity three minutes later.
Omekede fired Queens ahead again after picking a loose ball from the centre of the pitch to blast the back of the net in the 24th minute. Margaret Omweri extended the lead in the 32nd minute to send her side into the grand finale.
In the Nairobi East regional finals, Shrink Pack FC from Kasarani booked their place in the grand finale after beating Soweto Starlets 2-1 in another mouthwatering clash. With the match tied at 1-1 into the halftime break, it took effort for Shrink Pack to engineer a comeback to win the tough test.
Soweto was first on the score sheet as Sylvia Apondi put Nairobi East in the lead in the 45th minute. Shrink Pack recovered from the setback as Mary Kimani scored a brace in the 65th and 82nd minutes to cap their win.
Shrink Pack will now face off with South C Queens on Friday to determine the ultimate Sakaja Cup womens champion.
The men's division winner will ultimately take home a cool Sh3 million top prize, while the runners-up will receive Sh2 million and the bronze medalist will receive Sh1 million.