Facing a side of powerful runners packed with experience in both the Super League and NRL, the Bravehearts did not take a backwards step and got their just rewards at Derwent Park in Workington on Tuesday night.
Coach Steve McCormack enjoyed the time off from his regular job as schoolteacher after his side squandered a 20-4 halftime lead but galvanised themselves sufficiently to snatch victory thanks to fullback Russell and the reliable boot of Danny Brough - who landed five goals.
Even then Penrith-bound halfback Peter Wallace's team had to endure a last-second video referee decision - a sixth of the night - to get the job done.
"We were never going to give up. That 'do or die attitude' and the crowd really got behind us - when it really mattered the team dug deep," McCormack said.
"We have got a bit of improving to do in all areas."
Tonga scored five tries against four, and had Micky Paea's 80th-minute effort ruled no-try by the video referee, but were let down by some wayward goalkicking.
"A bit disappointing not to go away with the win. We wanted to (go for the try at the end) but it didn't happen. We'll have to bounce back," said Tonga forward Sika Manu, who scored two triers.
Tonga had a penalty for offside in the 79th minute, deep in Scotland's half, but decided to take a tap instead of going for the two points.
Tonga took an eighth-minute lead as Manu's delayed ball put fullback Glen Fisiiahi through.
Russell then dragged his way out of three would-be tacklers to open Scotland's account.
Brough added the extras and then tagged a penalty, with a tasty punch-up between the two sides keeping the fans enthralled.
Substitute hooker Ben Fisher scored Scotland's second try and despite some big hits from prop Fuifui Moimoi, Tonga conceded another try before the break.
Danny Addy's fine pass put Brett Carter in and Scotland's fortunes were summed up as Brough landed the touchline goal, with the ball bouncing off the bar and dropping over for a 20-4 halftime lead.
Sika Manu chipped away at the deficit immediately after the restart, and Tonga's roll continued apace as Nafe Seluini went over from close range after a string of Scottish errors.
Manu scored again, only for another failed conversion to leave Scotland two points ahead.
A knock-on from Ukuma Ta'ai cost Tonga another score, but Willie Manu put his side ahead 24-20 with 13 minutes left before Russell scored the clincher.