Despite his best efforts, though, Fabrizio could not break away, with Haslam and Smrz going with him as they lapped at a similar pace to Haga, now several seconds up the road.
Buoyed by his superb run to third position in the first race, Haslam kept Fabrizio under significant pressure, hounding the Italian through each bend but being unable to find his way through.
Nonetheless, the Stiggy's rider's perseverance paid off when he finally planted a move on lap 13, Haslam resisting Fabrizio's counter-attacks to move through and gradually pull away.
Crossing the line just over two seconds behind winner Haga, second place marks Haslam's best-ever WSBK result and brings to a close to an outstanding day that also sees him up to third in the overall standings.
The battle for third went down to the wire too, Fabrizio holding the position into the final lap, only for Smrz to get the better of him and record what is also his and Guandalini Ducati's best-ever result at WSBK level.
Some way behind, Jonathan Rea got a much needed boost with a run to fifth, the Northern Irishman recovering from another poor start to come out on top of a heated battle between himself and the sole Yamaha of Tom Sykes.
Keeping a watching brief just behind, Carlos Checa was seventh, with Shane Byrne eighth, Neukirchner ninth and Troy Corser tenth. Ruben Xaus followed in 11th after a race-long fight with Yukio Kagayama.
In a race that saw problems for Spies, Regis Laconi, Karl Muggeridge and Stuart Easton among others, the final three points paying positions fell to Brendan Roberts, Matteo Baiocco and Luca Scassa – all first time scorers at this level.
The WSBK field now heads south to Italy for the annual jaunt to the exciting and high-speed Monza circuit…