SYDNEY coach John Longmire has identified pacy youngster Zak Jones as a key weapon in the Swans' battle with in-form St Kilda at Etihad Stadium on Saturday. 

Jones has been one of his side's most consistent players over the first eight rounds of 2017, with his speed and ability to carry the footy one of his greatest assets.

The 22-year-old has played his best footy across half back during his 39-game career, but a move onball has seen him boost his average disposals from 14.9 last year, to 21.1 at 78 per cent efficiency, and he's ranked third at the Swans for metres gained with 414.6 per match.

Alongside All Australian trio Josh Kennedy, Luke Parker and Dan Hannebery, who are all elite midfielders but lack leg speed, the explosive and attacking Jones gives the Swans midfield an offensive weapon of a different kind.

Longmire said Jones would be extremely important given the Saints' amount of talent at ground level, so Jones' role this week remains up in the air, and he might see himself back in defence.

"It's a consideration for us, whether we make that call or not will probably depend on how the game is going," the coach said.

"They're a very good running team the Saints and he gives us some great run through the midfield.

"But we've lost (Jarrad) McVeigh from the half back line, (Jack) Billings kicked goals and was really dangerous last week, and their smalls are as good as any going around." 

The Swans were cruelled with injury early in the season and lost the opening six games of the year, but former co-captains Jarrad McVeigh and Kieren Jack are now the only two players from Longmire's best 22 to be definitely ruled out off Saturday's game. 

Kurt Tippett (hip) and Gary Rohan (concussion) got through a stint in the NEAFL last week unscathed, while Oliver Florent (rested), and All Australian defender Dane Rampe (arm) are others in line to play against the Saints.