They ended day four with a total of 335 points and a one lap lead over second place Kenny de Ketele and Moreno de Pauw of Belgium.

Victory in the opening race of the day went to Tristan Marguet and Claudio Imhof as the Swiss team attacked early in the 100-lap madison to strike an early blow.

Success would soon come for the overnight leaders, with Havik storming to a win in the 40-lap derny race in front of Germany’s Nico Hesslich.

Denmark’s Alex Rasmussen and Casper Pedersen then prevailed in the 500 metres madison time trial, with a well timed hand swing helping the duo set a time of 26.625 seconds.

There were two triumphs for Britain’s Andy Tennant and Chris Latham, with the former securing a win in the elimination race, after the latter had topped the field in the longest lap discipline.

Their success was split between a win for Imhof in the second derny competition, as the Swiss team continued their impressive day.

The day concluded with another German pairing of Leif Lampater and Maximilian Beyer taking a lap on the field to win the final madison race.

A well timed sprint for second place gave de Ketele and de Pauw some additional points to their tally to boast their chances of the overall victory.

The Amsterdam and London winners of the series trail Havik and Stroetinga by a lap, but they have a greater tally of 338 points.

Pim Ligthart and Jens Mouris lie third, with the pair a lap behind the leaders and with a total of 277 points.

Germany's Maximilian Levy leads the sprinters' classification, with Britain's Katie Archibald heading the women's event.