Telusa Veainu and Jack Ram scored two tries apiece as Tonga saw off Namibia 35-21 in an entertaining game at Sandy Park on Tuesday.
Coming in at the last minute, Veainu got Tonga off the mark after just five minutes, with Ram following that up inside the first 15 minutes.
Johan Tromp pulled one back for Namibia but Tonga were in control at half-time leading 22-7 after a try from Latiume Fosita.
Ram's second gave them the bonus point early in the second half, before two Jacques Burger tries, either side of Veainu's second, in an exciting encounter in Exeter.
The win takes Tonga up to second in the group, although with the games to come against Argentina and New Zealand, they remain long shots to reach the quarter-finals.
Namibia, meanwhile, are still chasing their first-ever World Cup win, but will have taken heart from a second impressive display in quick succession, following Thursday's valiant loss to the All Blacks.
The game started at a frantic pace, and Tonga took full advantage with an opening try after just five minutes from Veainu. Only included the last minute due to the withdrawal of Fetu'u Vainikolo, the Rebels winger collecting Fosita's inside ball before slicing through and showing his power to race over from halfway. Vunga Lilo converted to make it 7-0.
They quickly had their second, earning a couple of penalties at scrum-time before kicking into the 22 for an attacking lineout. Spotting some weak maul defence, Ram peeled off and sprinted over despite the attentions of Renaldo Bothma.
Despite Lilo's missed conversion, it looked like a stroll in the park for Tonga, but Namibia came straight back into it, benefiting from some nonchalance from their opponents. After Fosita was charged down from the restart, Sila Puafisi then knocked the ball on just outside his own 22, with Tjiuee Uanivi collecting and delivering the scoring pass for Tromp. Theuns Kotzè added the simple conversion.
Tonga were soon over again though, with Fosita showing sensational hands to finish from close range. After a clever move off the back of a lineout, Joe Tuineau's pass rolled across the ground but Fosita collected on the run and dotted down for the try.
The second half began in similar fashion to the first, as Veainu produced a searing break, this time setting up Ram for his second try. After collecting Kotzè's deep kick, Veainu spotted a gap in the chasing defence and went straight through before finding Ram outside him for the easy finish.
With that try, the bonus point was sewn up but Namibia fought back and scored their second try through their skipper Burger, just managing to get over the line after a strong maul. Kotzè slotted the touchline conversion to make it a two-score game once more.
Still, in Veainu, Tonga had the most dangerous player on the pitch, and after some good work from Siale Piutau, Ram turned provider with a wide pass to the winger, who showed his pace to get away on the left and score his second. Lilo missed the conversion but Tonga led 32-14.
Namibia weren't done yet though, and with quarter of an hour remaining Burger added his second, again off the back of a rolling maul, with Tonga nowhere in defence on this occasion.
Kotzè's conversion made it 32-21, but Kurt Morath, off the bench, slotted a penalty with eight minutes to go to push the lead back to 14 points, becoming his country's record points scorer in the process.
Namibia had their chances to score again, but couldn't find a way through, with a couple of knock-ons at the lineout late on, and it was Tonga who held on for the win.
Man of the match: Jack Ram was outstanding, but Telusa Veainu was in a different class. Almost unstoppable when he got the ball in space, he scored two and made another for Ram in a brilliant display.
Moment of the match: There were some cracking tries, but the best of the lot was Veainu's effort that was disallowed just before half-time. With no space to work in, Veainu put in an acrobatic dive and dotted down as the rest of his body was being bundled into touch. Unfortunately he used his left hand to keep his balance and just clipped the touchline with it as the ball was placed on the try-line.
Villain of the match: No nasty business to report.
Tries: Tromp, Burger 2
Cons: Kotze 3
Tries: Veainu 2, Ram 2, Fosita
Cons: Lilo 2
Pens: Lilo, Morath
Namibia: 15 Chrysander Botha, 14 Johan Tromp, 13 Danie Van Wyk, 12 Johan Deysel, 11 Russel Van Wyk, 10 Theuns Kotze, 9 Eneill Buitendag, 8 Renaldo Bothma, 7 Rohan Kitshoff, 6 Jacques Burger (c), 5 Tjiuee Uanivi, 4 Janco Venter, 3 Johannes Coetzee, 2 Torsten Van Jaarsveld, 1 Casper Viviers.
Replacements: 16 Louis van der Westhuizen, 17 Johnny Redelinghuys, 18 AJ De Klerk, 19 Tinus Du Plessis, 20 PJ Van Lill, 21 Damian Stevens, 22 Darryl De La Harpe, 23 David Philander.
Tonga: 15 Vungakoto Lilo, 14 David Halaifonua, 13 Siale Piutau (co-captain), 12 Sione Piukala, 11 Telusa Veainu, 10 Latiume Fosita, 9 Sonatane Takulua, 8 Viliami Ma'afu (co-captain), 7 Jack Ram, 6 Sione Kalamafoni, 5 Joseph Tuineau, 4 Hale T Pole, 3 Sila Puafisi, 2 Aleki Lutui, 1 Soane Tonga'uiha.
Replacements: 16 Paula Ngauamo, 17 Tevita Mailau, 18 Halani Aulika, 19 Tukulua Lokotui, 20 Opeti Fonua, 21 Samisoni Fisilau, 22 Kurt Morath, 23 Will Helu.
Venue: Sandy Park, Exeter
Referee: Glen Jackson (New Zealand)
Assistant referees: Chris Pollock (New Zealand), Federico Anselmi (Argentina)
TMO: Ben Skeen (New Zealand)