Southland held on for the first win of their NPC rugby campaign with a 20-16 victory over Waikato in an early evening cross-over match in Invercargill on Friday.

It's only the third time in 28 years that championship team Southland have beaten premiership side Waikato, who have just one win from four starts in this year's competition.

Waikato dominated the early exchanges but, despite huge advantages in territory and possession, could only manage a 9-0 lead through three Trent Renata penalties after 25 minutes.

Southland's lineout put real pressure on the Waikato throw, but any gains were squandered through ill-discipline as the visitors continued to give away too many kickable penalties.

Both teams had difficulty hanging onto the ball, with Waikato's handling and passing accuracy consistently letting them down.

The only try of the opening 40 minutes came on the half-hour mark. Centre Cardiff Vaega dived over after good pressure from a charge down caught Waikato halfback Kylem O'Donnell with nowhere to go on his line.

Marty McKenzie slotted the conversion, then followed that up with a 37th-minute penalty which gave the home team an unlikely 10-9 lead at halftime.

Big lock Josh Bekhuis extended the lead seven minutes after the restart, crashing over after Vaega's line break and Michael Fatialofa's drive finally gave Southland some front-foot ball.

Waikato's woes at the breakdown continued in the second spell, and their error rate proved especially punishing when Semisi Masirewa dropped the ball in reaching out for what looked a certain try in the left corner.

But Masirewa made no mistake as the game neared 70 minutes, finishing off a well-worked move from an attacking scrum after Southland halfback Tayler Adam was binned.

Masirewa latched onto a well-weighted skip pass from second-five Joe Perawiti, and Renata's conversion cut back Southland's lead to 17-16.

Another McKenzie penalty with five minutes remaining gave Southland a little breathing space, and they controlled the closing minutes comfortably to wrap up the win.