David Hille is a certain inclusion for Essendon's big assignment against St Kilda on Friday night, but coach Matthew Knights has said he's otherwise reluctant to change a winning line-up.

Hille, who hasn't played since tearing a hamstring against the Swans at the SCG in Round 11, is entitled to expect to be eased back into action.

But, according to Knights, the 29-year-old will be required to hit the ground running in a support role for Paddy Ryder in the ruck.

"He's a big 'in', David," said Knights at Windy Hill on Thursday morning.

"Unquestionably, he's probably our most important player because he can play ruck and forward."

"We're expecting David to compete and play his role, but after seven weeks we've got to be realistic also."

Hille's return will help to offset the loss of Jason Winderlich who'll miss 1-2 weeks after undergoing surgery to repair a broken bone in his hand.

Knights said he would prefer to keep last week's winning line-up against North Melbourne intact as far as possible, which means that Andrew Welsh is likely to return via the VFL after a fortnight out with a groin.

Despite appearing hobbled by a calf injury against the Kangaroos, skipper Jobe Watson will be fit, according to his coach, to lead the Bombers into action against the Saints.

"Jobe, every week, because he plays on the inside, gets knocks and bruises but no different to any other AFL footballer that plays a similar role," Knights said.

"He's just got a few corkies and the likes but that's not going to stop him from playing."

"If it was a strained calf he wouldn't be playing because you wouldn't do that to a player."

While Knights rates the Bombers as "rank underdogs" on Friday night, they happen to be the only team in the competition to have beaten the Saints in their past two outings.

"We have been in decent form when we've played them and have had a settled 22 and most of our players available," said Knights.

"The times we've played the Saints in the last couple of years there's probably been a lot of elements in our favour."

"Obviously the guys have stepped up on the big stage and played to their maximum."

Knights said the mood at Windy Hill had been upbeat coming off the win over North which broke a six-game losing streak.

The plan over the closing weeks of the season, he said, is for more of the same.

"The last five or six weeks was going to be all about getting some respect back, particularly after the three poor weeks," Knights said.

"I think we took a small step last week."

"I'm not saying we've solved everything with our game, but we're on the up a little bit after last week."

Knights said he's "comfortable" with assurances from the AFL and the management at Etihad Stadium that everything is being done to prepare the best possible surface for Friday night's match.