South Africa took a major step towards winning their first-ever Cosafa Cup in a riot-marred first leg of the final in Blantyre, beating Malawi 3-1.

The result gives South Africa a healthy two-goal advantage with the second leg to come in Durban next Saturday.

Patrick Mayo played a starring role, scoring from two goalkeeping errors before setting up Jimmy Kauleza for the third.

It took until 42 minutes for the deadlock to be broken, when Malawian goalkeeper Navigator Dzinkambani let a bouncing ball slip out of his fans and onto the head of Mayo.

But a handball by defender Thabang Molefe gave Malawi an equaliser just before the interval, with the resultant penalty converted by Patrick Mabedi.

Mayo soon restored the visitors' lead, however, when Dzinkambani mistimed his run to the ball and Mayo was able to steer home into an empty net.

The final nail in Malawi's coffin came two minutes from the end, when Mayo - who could have claimed his hat-trick - instead unselfishly laid the ball square to Kauleza.

Kauleza could even afford to fumble his first touch, but still netted.

The third goal set off a barrage of missiles from frustrated fans, delaying the end of the game for more than five minutes.

"Our mistakes cost us," said Malawi's shell-shocked coach Kim Splidsboel.

"I have a big job to lift the players for the second leg."

South African coach Ephraim Mashaba said he might use the second leg to experiment with a few new caps, after using five uncapped players in Saturday's match.

Malawi can expect a fine from Cosafa for the behaviour of their fans, who had filled the 60,000-capacity stadium five hours before kick off in expectation of humbling one of the top-ranked sides in the region.

Both teams were playing in the final for the first time despite South Africa having been long-standing top-ranked side in the competition.