Jonathan Rea may have been unable to contain the Ducati of Scott Redding in Saturday's opening World Superbike race at the Navarra circuit, but he still increased his world championship lead by four hard-fought points.

Starting on pole position, the Kawasaki rider lost the holeshot to Redding into turn one, but swiftly retaliated a few corners later to lead the field for the opening laps.

However, Redding kept in his wheeltracks and ultimately slipstreamed around the ZX-10 rider on the home straight at the start of lap 6 of 23.

Some big moments for Rea, including a front-end slide that sent his outside foot waving in the air, helped the Englishman escape to a 2.5-second victory, but Rea was still a safe 3.4s clear of nearest title rival Toprak Razgatlioglu, in third.

"I was a little bit nervous about the start of the race. It was very important to be at the front and we had quite a good start, but Scott was just a little bit better," Rea said.

"At the beginning I felt I could go to the front and when Scott went quite wide in T5 and T6 I went on the inside and passed him. From there I just kept my rhythm until he blasted me on the straight.

"After that I thought, ’I’m there’ but then the front started to heat up, stability started to go down and the front was moving.

"Over-pushing the front, I had a few slides and enough to tell me to brake a bit earlier. I lost as much as one-second during one mistake and Scott went away.

"I did not feel he was destroying us lap-by-lap when it was constant, the gap was quite similar.

"I felt really good in the first two sectors, stronger than Scot, but I was pushing the front too much in those slow turns from Turn 9 to the end of the lap. But I could control the gap to Toprak quite easily.

"Hopefully we can make some changes on the front tomorrow to make a step forward.”

Rea will start Sunday's pair of races with a seven-point lead over Razgatlioglu, with Redding 45-points adrift in third.

Team-mate Alex Lowes finished in fifth place.

"I had a good start and was fourth until Toprak passed me," said Lowes. "I thought I would sit behind those guys out front but I wasn’t fast enough because I was struggling with the front.

"I was a bit quicker than the guys behind so it was a bit of a boring race for me. But it was a long race - and hot. I used the Race One experience to try to be consistent and understand how I can improve for Sunday.”