Their defeat to Bedford Blues in the British & Irish Cup aside, Llanelli have been on a good recent run, with consecutive wins over Cardiff, Swansea and Bedwas.
A visit to The Gnoll to take on SWALEC Cup finalists Neath now awaits and Buchanan knows just how tight it is at the top of the table.
"It's come down to a situation where we have to win all our games," he said.
"It couldn't be tighter as we come down to the last couple of games and it's hugely important to keep up the momentum.
"And the most important thing is it's in our own hands."
Llanelli were narrow 7-6 winners over Bedwas last Saturday, Nick Reynolds scoring the only try of the game. He starts at centre tonight alongside Steffan Hughes with Jordan Williams at outside half. Adam Powell captains the side from lock with loyal Llanelli servant Craig Hawkins at hooker.
While tonight's game is vital for Llanelli's championship hopes, there could still be a few twists and turns before we find out who will play Pontypridd in the final.
"It's quite a unique situation and Llandovery have to play Bedwas so that's some consolation for us as there'll have to be a loser there," acknowledged Buchanan.
"You always face a tough game at The Gnoll and tonight will be no different. Neath's league position is a bit deceptive as on their day they can beat anybody.
"We're going to have to be at our best to have a chance of beating them."
For Neath, changes are expected after their cup semi-final win over Aberavon on Sunday. They themselves face a tough run of fixtures, a clash with Llandovery on Saturday following tonight's game.
"There'll have to be changes on Wednesday as we've Llandovery three days after that," said Neath head coach Pat Horgan following their progression to the Millennium Stadium final.
"We've a few bumps from the Aberavon game so it worries me that such a strain has been put onto a small squad but we'll get through it.
"We had some fantastic support on Sunday and we look forward to seeing everyone back at The Gnoll this Wednesday."
Llanelli: 15 Johnny Lewis 14 Kristian Phillips 13 Nick Reynolds 12 Steffan Hughes 11 Dale Ford 10 Jordan Williams 9 Justin James, 1 Rhys Thomas 2 Craig Hawkins 3 Jamie Kaijaks 4 Adam Powell [c] 5 Nathan White 6 Lewis Rawlins 7 Duane Eager 8 Stuart Leach.
Replacements: Tom Sloane, Kirby Myhill, Chris Davies, Dan Thomas, Ryan Jones, Dion Jones, Chris Keenan, Ben Leung.