"There are top-quality teams fighting for it [the title] and we can't afford to lose too much ground on them."
The England international was also keen to give his view on the incident against Shakhtar when Alex Teixeira claimed a penalty after being challenged inside the box in the first half.
"I think I just nipped in," he insisted. "He was already on the way down and I think that's why the referee didn't give it. I'd have been disappointed if he'd have given a penalty for that."