Sri Lanka must defend 203 all out to move level on points with England in the World Cup standings after labouring with the bat against South Africa at Chester-le-Street.
One week after a shock victory over the tournament hosts, Sri Lanka faltered badly after reaching 67 for one before the end of the first powerplay, several of their batsmen enduring painstaking stays at the crease.
Most of them were architects of their own downfall, eight of their top nine reaching double figures but no one going beyond 30, while Dwaine Pretorius' three for 25 was the most economical 10-over analysis of the tournament.
A swarm of bees sweeping over the ground shortly before the end of the innings led to the players and umpires briefly lying face down on the floor, before Chris Morris (three for 46) claimed the final wicket as Sri Lanka were all out after 49.3 overs.
A slow surface means South Africa, already eliminated from contention for the semi-finals, face no routine chase as they look to put a dent in Sri Lanka's bid to reach the knockout stages.
South Africa won the toss and made immediate inroads as Dimuth Karunaratne was out first ball, unable to lower his hands to a lifting delivery from Kagiso Rabada and sending a looping catch to second slip.
Avishka Fernando displayed similar carefree abandon as he had in the shock win over England last week, upping the scoring rate amid some loose strokes in a 67-run stand alongside Kusal Perera.
Fernando departed for 30 from 29 balls when he miscued to Faf Du Plessis back-peddling from mid-off off the bowling off Pretorius, who had his second wicket in his next over when Perera chopped on, having also contributed 30.
The pair's dismissals marked an extended period of stagnation for Sri Lanka, Kusal Mendis and Angelo Mathews progressing at a snail's pace as a position of 67 for two after the first powerplay became 91 for three at the end of the 20th over.
Seeking to cast off the shackles, Mathews, whose unbeaten 85 held the innings together against England, chopped Chris Morris on to his stumps for 11 while Mendis' ponderous 23 came to an end when he slapped Pretorius to cover.
At 111 for five, a competitive total seemed a distance away but Dhananjaya de Silva did at least show a little intent, coming down to Imran Tahir and driving sumptuously through cover for the first boundary in 59 deliveries.
However, he missed a reverse sweep off JP Duminy's first ball to be bowled for 24 while Jeevan Mendis hooked Morris to long leg for 18, the pair both trying to inject some urgency into proceedings after starting slowly.
Between the start of the 11th over and the end of the 40th, Sri Lanka had added only 96 runs and matters barely improved thereafter.
A swarm of bees sweeping over the ground was a momentary distraction, after which Sri Lanka surpassed 200 but failed to bat out the 50 overs.
