They quickly took advantage of the new rule change which means every rally now scores a point to claim an early 11-4 advantage through John Gilling, Pete Abraham and skipper Tom Young.
Wessex gathered momentum with England internationals Tim Hollis and Morph Bowes starring as they eroded Riga's lead to take the set 25-17.
The visitors struggled from the beginning of the second set. Their attack was almost non-existent and they only re-asserted themselves in the latter stages despite going down 25-16.
Riga changed their line-up in set three and saw an immediate change in their fortunes. The Warwick-based team established a 12-8 advantage thanks to big Richie Meade.
Neither team seemed capable of taking control and Riga saved one match point and then levelled the scores at 24 points each. Wessex sealed the match with two fine attacks to win the set 26-24.
"The lads did well, perhaps .not as well as they have been lately but we still had our chances to take two of the sets," said Young. "We took the foot off the gas in the first set and paid the price. I'm disappointed but I still think we'll do things this season, so I've got no worries!"
Riga will be aiming to bounce back at Liverpool on Saturday.
Riga's women's team had an impressive. 3-0 victory over RAF-based Hawks at Warwick's St Nicholas Park Leisure Centre to get their season-off to a flying start.
