Tonga came from 13-5 down to beat the United States 22-13 in a Test on the north Wales coast on Saturday.
Tonga overcame having two men yellow-carded in the second half to post a fourth straight win over the Eagles. The Tongans also won the first match of their European tour after losing to Italy and English club Newcastle.
Despite a third match in a week, Tonga scored in the first minute through wing Viliami Helu. His opposite number, Luke Hume, then had a try disallowed for a forward pass. Fullback Zach Pangelinan, on debut, gave the Eagles their first points from a penalty.
The Eagles employed effective pick-and-go tactics, and eventually went 10-5 ahead on half-time when scrumhalf Robbie Shaw finished an attack by centers Paul Emerick and Andrew Suniula.
But after Tonga flyhalf Fangatapu Apikotoa was sin-binned for interference and Pangelinan kicked the resulting penalty for 13-5 in the 45th, the Eagles' effort dropped away.
Backup Tonga kicker Vungakoto Lilo began the comeback with a penalty, and Apikotoa returned to convert lock Joseph Tuineau's try from a break by Taniela Moa.
Tonga held the two-point lead comfortably through the last quarter, securing the win four minutes from time when inside centre Sione Piukala took Apikotoa's between-the-legs pass and burst past three defenders to cross. There was enough time left for replacement Alipate Fatafehi to be sin-binned for a high tackle.
Tries: Helu, Tuineau, Piukala
Cons: Apikotoa 2
United States: 15 Zachary Pangelinan, 14 Cornelius Dirksen, 13 Paul Emerick, 12 Andrew Suniula, 11 Luke Hume, 10 Toby L'Estrange, 9 Robbie Shaw, 8 Todd Clever (captain), 7 John Quill, 6 Scott Lavalla, 5 Louis Stanfill, 4 Brian Doyle, 3 Eric Fry, 2 Chris Biller, 1 Shawn Pittman.
Replacements: 16 Derek Asbun, 17 Nick Wallace, 18 Zachary Fenoglio, 19 Inaki Basauri, 20 Peter Dahl, 21 Mike Petri, 22 Roland Suniula, 23 Gearoid Mcdonald.
Tonga: 15 Vungakoto Lilo, 14 Viliami Helu, 13 Sukanaivalu Hufanga, 12 Sione Piukala, 11 Fetu'u Vainikolo, 10 Fangatapu Apikotoa, 9 Taniela Moa, 8 Viliami Ma'afu, 7 Nili Latu (captain), 6 Steve Mafi, 5 Lua Lokotui, 4 Joseph Tuineau, 3 Halani Aulika, 2 Elvis Taione, 1 Alisona Taumalolo.
Replacements: 16 Ilaisa Ma'asi, 17 Kisi Pulu, 18 Tevita Mailau, 19 Hale T Pole, 20 Joshua Afu, 21 Viliame Iongi, 22 Edmond Paea, 23 Alipate Fatafehi.
Referee: Francisco Pastrana (Argentina)
Assistant referees: Tim Hayes (Wales), Wayne Davies (Wales)