Matavesi, who moved to Saints from Cornish Pirates in early December, started life at Franklin's Gardens in the hooker position.
But with Mike Haywood, James Fish and Reece Marshall all now fit, Matavesi was given a chance at No.6 for the Wanderers against Sale Jets.
And it proved to be an inspired selection as Matavesi, who played for Fiji at the recent World Cup in Japan, excelled from the off.
He won three breakdown penalties in the opening 15 minutes alone, continuing to steal Sale ball all night while also etching his name on the scoresheet.
The other highlight from a Northampton perspective was the return of Marshall, who was making his first appearance since suffering a hamstring injury in Saints' defeat at Exeter last May.
He looked strong and hungry, coming through unscathed, and so did the likes of Ryan Olowofela and skipper Harry Mallinder, who oozed class as he got a full 80 minutes under his belt.
But it was Matavesi who really caught the eye from the start, immediately earning two breakdown penalties to win the ball back for the Wanderers in defence.
When the hosts eventually got up the other end of the field, some slick passing put Sale under real pressure.
Tommy Freeman almost got the ball down but he was stopped just short before Matavesi won yet another penalty in defence, allowing the Wanderers to get more possession, which they were to use to great effect.
Olowofela, starting at outside centre, was the man on the mark as he made a scything run before showing good strength to resist the attentions of the Sale defence for a superb try.
Tommy Mathews converted to make it 7-0 on 15 minutes and the Wanderers kept coming, eventually powering over through prop Karl Garside.
Mathews added the extras and Matavesi was soon at it again in defence, making a big hit to prize the ball from Sale's clutches.
It was turning out to be an all-action showing from the Saints No.6, who soon popped up with a try, proving far too strong for the Sale defence.
Mathews made it 21-0 with the conversion and the Wanderers were soon at the door again as big contributions from Olowofela and Marshall gained ground before Mathews found Freeman out wide with a fantastic lofted pass.
It was all too easy for the hosts, who were 28-0 up after Mathews converted again.
And the try of the game so far came four minutes before the break as Josh Gillespie started and finished a move that also included full-back Mallinder, who provided the final pass with some good awareness from the floor.
Mathews converted and Sale looked all at sea, but they did finally manage to build up some pressure before the break, winning a succession of penalties close to the home line.
And eventually the Wanderers wall cracked as scrum-half Raffi Quirke dived over, allowing Kieran Wilkinson to convert, leaving Sale 35-7 down at the break.
Mallinder did some good work to stop Sale scoring just after the restart, covering well and bundling wing Curtis Wilson out of play.
But it wasn't long before the Jets did grab their second of the night as a lineout was stolen and Joe Sproston powered over.
Wilkinson missed the conversion and the Wanderers almost responded as Gillespie sent Freeman through a gap, but the wing was held up after some lovely footwork took him over the line.
But Sale couldn't resist for long as some patient play was rounded off by centre Fraser Strachan.
Mallinder took over kicking duties to convert and the Wanderers then pieced together a fantastic flowing move, started by replacement Morgan Dayes and finished out wide by another guest player, Ampthill forward Rob Langley.
Mallinder missed the tricky touchline conversion but the Wanderers were cruising again at 47-12 up and Dayes soon made another big contribution as he scored in the corner.
It took the Wanderers to their half-century, and Mallinder added more gloss to the scoreline with the touchline conversion.
Promising wing Gillespie showed he was still switched on as he raced back to stop lively Sale scrum-half Quirke scoring his second.
Gillespie almost scored late on, just being pushed into touch at the last, but it mattered not as the hosts ran out convincing winners.
Wanderers: Mallinder (c); Freeman, Olowofela (Dayes), Strachan, Gillespie; Mathews, Tupai (J Mitchell 40); Trinder (Iyogun), Marshall (Hughes 70), Garside (Prowse); Langley (van Vuuren), Onojaife; Matavesi (Betteridge 68), Newman (Robinson 68), Uru.
Sale Jets: Magee (Yorkshire Academy); Botha (Fylde), Doherty, Roebuck, Wilson (Doncaster Knights); Wilkinson, Quirke; Carlile, Ashman, Jones; Birch, Sproston (Doncaster Knights); Jackson (Yorkshire Academy), Smith (Yorkshire Academy), Dugdale.
Replacements: Holling (Doncaster Knights), Pope, Ford, Wolfenden (Manchester Metropolitan University), Cullen (Doncaster Knights)