Wales battled back to earn a stuttering victory over ill-disciplined, 14-man Fiji.
With Fiji leading 13-7, wing Eroni Sau was sent off for a reckless swinging arm on Johnny Williams in the 25th minute.
The visitors also picked up two yellow cards.
Hooker Ryan Elias scored twice with Kieran Hardy, Alex Cuthbert, Louis Rees-Zammit and Liam Williams also scoring as Wales finished strongly.
Wales host Australia next Saturday to end their autumn series, having lost to New Zealand and South Africa before overcoming Fiji.
The visitors underlined their attacking threat with two tries from Waisea Nayacalevu and 13 points from Ben Volavola, but will be left to rue their indiscipline with playing periods of the game with 13 men despite leading 10-0, 13-7 and 23-14.
Wales were sloppy and their attacking play lacked cohesion for long periods and were indebted to a sensational late score from wing Rees-Zammit, while full-back Liam Williams impressed on his international return and ran in the final score.
Wayne Pivac's side will be grateful for the victory after two defeats against New Zealand and South Africa but will require a marked improvement in the final autumn international against Australia next weekend.
It was a frantic encounter which Wales coach Pivac would have known to expect having been in charge of Fiji between 2004 and 2007, while the visitors were led by a Welshman in Gareth Baber.
He was heading up a temporary Fiji coaching staff for the autumn international fixtures because head coach Vern Cotter and the team's other southern hemisphere-based coaches were not involved due to travel restrictions.
Wale were affected by late changes with prop Tomas Francis ruled out with concussion and Will GriffJohn promoted to make his first start. Josh Adams was a very late withdrawal with a calf injury suffered in the warm-up with Nick Tompkins replacing him at centre.
Francis and Adams joined a lengthy casualty list that includes Alun Wyn Jones, Ken Owens, George North, Leigh Halfpenny, Taulupe Faletau, Justin Tipuric, Josh Navidi, Ross Moriarty, Dan Lydiate and Wainwright.
Fiji took advantage of Wales' disrupted build-up by compiling an early 10-point advantage.
Number eight Viliame Mata burst through and released centre Nayacalevu for the opening score as Volavola converted and added a penalty.
The physical nature of the opening exchanges was highlighted when John only lasted seven minutes on his first start before leaving with a head injury to be replaced by Dillon Lewis.
Wales settled down and responded with a try for hooker Elias from a driving lineout with Biggar converting.
Volavola slotted over a second penalty before wing Sau was red carded for the needless swinging arm.
English television match official Stuart Terheege alerted referee Nic Berry to the incident and also persuaded the Australian official to give a red, rather than a yellow card.
Wales had a man advantage but kept making basic errors typified by a loose Hardy pass to Rees-Zammit, while the hosts continually lost the ball at the contact area with Fiji hooker Sam Matavesi outstanding in this facet.
More concerted Welsh pressure led to Fiji being reduced to 13 men when flanker Albert Tuisue was shown a yellow card for the team's persistent offending.
The home side made their two-man advantage tell with Hardy sniping over unopposed from a scrum and Biggar converting to give Wales the lead for the first time.
Wales appeared to have scored a third try with Rees-Zammit collecting a Biggar chip kick, but it was ruled out because earlier in the move the wing was deemed to be out of play when retrieving possession.
Wales led 14-13 at the interval, but a high tackle from Adam Beard on Frank Lomani allowed Volavola to restore Fiji's advantage despite still having 13 men.
Some Fiji magic followed. Full-back Setareki Tuicuvu took a quick free-kick tap penalty and released Vilimoni Botitu and he gave the try-scoring pass to Nayacalevu, who cantered away for a converted try.
The brilliance was tempered by the ill-discipline as Fiji were again reduced to 13 men when replacement prop Eroni Mawi was shown a yellow card and Elias went over for his second score from a driving lineout.
Replacement centre Willis Halaholo initiated some urgency in the Welsh backline and Cuthbert profited with an expert finish as Wales regained the lead.
Exeter's 19-year-old lock Christ Tshiunza was given his international debut as a replacement while another young star delivered.
Rees-Zammit produced a brilliant individual try as he sprinted onto his own kick with the score awarded after consultation between the officials, who decided he grounded the ball.
Man-of-the-match Williams sealed the victory with a late try, but the 15-point victory flattered the hosts.
Wales: L Williams; Cuthbert, Tompkins, J Williams, Rees-Zammit; Biggar, Hardy; Carre, Elias, John, Rowlands, Beard, Jenkins (capt), Young, Basham.
Replacements: Roberts, Thomas, Lewis, Tshiunza, S Davies, T Williams, Sheedy, Halaholo.
Fiji: Tuicuvu; Tuisova, Nayacalevu (capt), Botitu, Sau; Volavola, Lomani; Ravia, Matavesi, Doge, Ratuniyarawa, Mayanavanua, Tuisue, Kunavula, Mata.
Replacements: Togiatama, Mawi, Atalifo, Ratuva, Dakuwaqa, Matawalu, Naqalevu, Tuimaba.
Red card: Sau (25)
Match officials
Referee: Nic Berry (Australia)
Assistant Referees: Ben O'Keeffe (New Zealand), Gianluca Gnecchi (Italy)
TMO: Stuart Terheege (England)