Shaun von Berg claimed four out of seven wickets that fell to spin as the Titans strangled the log-leading Dolphins in their Momentum One-Day Cup clash in Durban on Sunday to win by 33 runs on the Duckworth/Lewis method.
The leg-spinner took 4/40 in his allotted seven overs as the visitors bowled their hosts out for just 155 in pursuit of a revised 189 victory target at Sahara Stadium Kingsmead.
Von Berg's effort came after his captain Albie Morkel caught the hosts off-guard by opening with part-timer Aiden Markram and Proteas spinner Tabraiz Shamsi with the pair returning figures of 2/28 and 2/23 on an up and down wicket.
There were also three wickets from Junior Dala (3/26) as the home side failed to come to grips with the pitch despite restricting the visitors to 204/8 after winning the toss and bowling first after a delayed start caused the match to be altered to a 40-over affair.
Farhaan Behardien top-scored with 45 and Morkel made 38, before David Wiese blasted 37 off 25 to ensure the innings ended with a bang.
Prenelan Subrayan (2/32), Andile Phehlukwayo (2/46) and Robbie Frylinck (2/40) all took two wickets.
The Dolphins' chase never got going after Markram dismissed Morne van Wyk (4) and Cameron Delport (2) within the space of four deliveries. It meant the hosts were in early trouble on 7/2.
Sarel Erwee made 38, before a rain delay altered the match situation slightly. However, the Dolphins were never really in the chase despite Khaya Zondo making 38.
And once he was trapped lbw by Shamsi, the end came quickly as the home side suffered a major blow in their quest to secure an automatic ticket to the final.
Although they remained top of the table, the Titans are now just a point behind with a game in hand heading into the last week of action.