Rea beat Davies by just 0.042s across the line as they battled hard to the last corner, with Sykes completing the podium. Rea, Davies, Sykes, works Yamaha rider Alex Lowes and Melandri on the second factory Ducati all taking turns in the lead.
Lowes briefly led mid-race and would eventually finish fourth, crossing the line little more than a second behind Rea and just 0.032s behind Sykes.
Melandri made a spectacular return to the championship in his first World Superbike race since 2014, taking the lead off the line and running at the front for several laps only for his day to end in frustration after a crash at the Southern Loop with eight laps to go.
An excellent showing from Leon Camier on a factory MV Agusta saw him cross the line three seconds behind race winner Rea to complete an all-British top five.
A solid start to the season by Xavi Fores (Ducati) and Jordi Torres (BMW) saw them take sixth and seventh respectively, with Eugene Laverty (Aprilia), Michael van der Mark, in his first race for the Yamaha factory team, and Randy Krummenacher (
After his solid fourth in Race 1 on Saturday Lowes made an excellent start from the head of the reshuffled Race 2 grid to lead the way in the opening stages, with Laverty and Fores also getting in the mix early on. Rea soon came through from ninth though, making light work of the challenge of the new regulations for 2017 which sees the grid reshuffled on Sunday further to the Race 1 results.
Rea took over in the lead with 17 laps to go, as Davies also soon came through to contest the lead, with Lowes fighting to stay with them for a podium result.
Melandri emerged as a contender in the second half of the race, having steadily fought his way to the front from 10th on the grid after his World Superbike comeback on Saturday ended in a crash. He was delighted to return to the podium at the end of Race 2 as he kept Rea and Davies in his sights.
A superb last lap battle between four riders for podium positions saw Rea come out on top again, with Davies a close (+0.025s!) second and Melandri third after an excellent ride, just 0.249s adrift, while Lowes collected more good points for Yamaha in fourth.
Fores finished fifth, while Sykes ended up at the back of a group of six riders who had been battling for the podium positions.
Behind that front group, Van der Mark and Camier crossed the line in seventh and eighth respectively, with Milwaukee Apruilia duo Lorenzo Savadori and Eugene Laverty rounding out the top 10.
The first race of the year brought drama with Roberto Rolfo (MV Agusta) beating Lucas Mahias (Yamaha) by just +0.001s across the line, with Anthony West (Yamaha) third.
The race was red-flagged after a big crash for Robin Mulhauser (Honda) and Gino Rea (
In a shortened and restarted 10-lap race, Rolfo held his nerve on the finish straight to edge Mahias out by the narrowest of margins over the
The restarted race gave Baldolini and Jacobsen a second chance, with Baldolini having crashed and Jacobsen having dropped back through the field with an apparent technical issue just before the red flag.
But it was not Jacobsen’s day as he ran off track at turn 10 early in the restarted race and eventually finished five seconds back from the front group in sixth.
There was last lap drama as Jules Cluzel (Honda) and Federico Caricasulo on the second works Yamaha had a spectacular collision at MG corner when both were in contention for victory, with another front runner, Alex Baldolini (MV Agusta) also suffering and falling back to finish 13th.
Veteran rider West took a popular third place as a wild card, with Kyle Ryde (
Pole man PJ Jacobsen (MV Agusta) crossed the line sixth after a hectic afternoon, with Aiden Wagner (Honda), Kazuki Watanabe (Kawasaki), Nacho Calero (Kawasaki) and Lachlan Epis (Kawasaki) completing the top 10.
Defending champion Kenan Sofuoglu (Kawasaki) was absent due to a pre-season hand injury which meant he would miss the opening two rounds of the 2017 championship, the Turkish rider looking to come back in style early in April at MotorLand Aragon in Round 3.