Jets running back Joe McKnight was back on the practice field yesterday and he expects to be on the MetLife Stadium field Saturday when the Jets face the Giants. “I’m playing Saturday” McKnight told The Post. McKnight has been dealing with a head injury that the Jets have not labeled as a concussion. It has kept him out of the team’s first two preseason games and he missed most of last week’s practices. McKnight practiced but was wearing a red jersey — meaning no contact. McKnight said the next step in his return to the field is being cleared for contact. It has been an eventful training camp for McKnight who failed his initial conditioning test was arrested for outstanding traffic violations and has clashed with the media. * Jets fans could be seeing wide receiver Santonio Holmes sooner than expected. General manager John Idzik sounded as optimistic as anyone has in the organization about Holmes’ return yesterday morning on WFAN. “Hopefully we’re close” Idzik said about Holmes returning to practice. Idzik said Holmes currently on the physically unable to perform list has been running and cutting. Before Saturday’s preseason game with the Jaguars Holmes was running at full speed and catching passes from quarterback Geno Smith.