Peter Siddle has been set the task of relocating the yard of speed he has lost over the course of a taxing 18 months, after he was dropped from Australia's side for the decisive third Test against South Africa at Newlands.

An ever-present member of the Australian pace attack since his recall to the team in Sri Lanka in 2011, Siddle had played 31 Tests out of 34 since that time. He missed two matches in the West Indies through injury in 2012 and a third against South Africa in Perth later that year, after he was left fatigued and carrying a hamstring niggle due to his exertions in the second match of that series in Adelaide.

Otherwise Siddle has been a highly reliable component of the bowling attack, repeatedly breaking partnerships and complementing the other fast men in the manner of Merv Hughes. However the treadmill of back-to-back Ashes series plus the tour of South Africa had begun to wear on Siddle's pace.

Australia's coach Darren Lehmann said he had preferred James Pattinson as a third quick in Cape Town for precisely that reason. The decision leaves Siddle with some work ahead to regain his place for Australia's next Test assignment against Pakistan in Dubai.

"He's fully fit, we just wanted the extra pace and James gives us that," Lehmann said. "They're producing wickets which don't have much grass on them and take reverse, so we want the extra pace here and he's a fresh bowler, which is great. He's as keen as mustard.

"Unlucky for Sids because he's done a great job for us over the last few Tests but we've gone for the extra pace. He'd like some more wickets obviously but it's the pace drop. We need him bowling 140kph and at the moment he's averaging 131, 132. He knows that, we've spoken to him and I'm sure he will be back bigger and stronger."

Pattinson's inclusion, for what is remarkably his first appearance in a first-class match since he was invalided out of the Lord's Test match last year, was made more palatable by the return of Shane Watson as a fifth bowling option. He and Nathan Lyon can be expected to bowl tight supporting spells while Pattinson, Mitchell Johnson and Ryan Harris pursue a more aggressive plan of attack.

This blueprint left no room for Shaun Marsh, who was left out despite a hundred in the first Test at Centurion. Lehmann said the selectors had followed the order of preference they had started the tour with, favouring Alex Doolan as the No. 3 batsman.

"We love to have five bowlers. Shane's pulled up well, he's good to go so it's nice to have the allrounder back, which gives us another option," Lehmann said. "It's always tough. We had to make a choice and that's the difficult job as selectors. We have to get 20 wickets to start with and obviously make a lot of runs.

"Shaun is very unlucky. At the start of the tour we were probably going to shape up as we have today."

Daniel Brettig is an assistant editor at ESPNcricinfo. He tweets here