England sweat on Ollie Robinson's fitness

England are sweating on the fitness of Ollie Robinson after the seamer suffered a back spasm early on the opening day of the fifth Ashes Test in Hobart.

England bowling coach Jon Lewis concedes Ollie Robinson needs to work on his fitness after the seamer suffered a back spasm that continues to bother him on day two of the fifth Ashes Test.

Robinson removed David Warner and Steve Smith cheaply with the new ball but was able to bowl just eight overs on day one as Australia rebounded to 6-241.

England confirmed on Saturday that Robinson is still struggling and won't be able to bowl in the day's opening session.

However, the paceman is expected to take the field.

The tourists are upbeat Robinson will be able to roll his arm over at some point in the day-night Test.

England, already without the bowling services of allrounder Ben Stokes because of a side strain, were forced to turn to 10 overs of spin from captain Joe Root on day one.

"At the moment, from what I gather, he has a back spasm," Lewis said.

"Those things can come and go. We're hoping with treatment overnight ... he can be free enough to bowl."

Lewis said the decision to leave Robinson on the field was to ensure he'd be allowed to bowl again on Saturday.

Robinson, who is England's leading wicket-taker for the tour with 11 despite being rested from the fourth Test at the SCG, was in his element on a green-top Bellerive Oval deck.

However, Lewis said the 28-year-old needed to improve his fitness, describing it as "definitely a work-on".

"It's something he needs to improve. He's got a record of playing a lot of games of county cricket," Lewis said.

"Playing international cricket is a higher intensity and you play all year around. He's got to get used to understanding what it takes to be a full-time, year-round international cricketer.

"In the times we're in, everything is really squashed together. There's not a great deal of rest and recuperation between games.

"That's something he is going to have to deal with. It is one of his things he really needs to work on."

Stuart Broad (2-48) shouldered 18 overs of the 59.3 bowled on a day that was cut short due to persistent drizzle.