Sheffield United ask Liverpool for guidance during the closing stages of the window

Despite insisting United view themselves as genuine contenders for play-off qualification ahead of this evening’s match at Peterborough, Heckingbottom warned a shortage of centre-halves could spell “trouble” if injury or illness strike.

The United manager has only three tried and tested options at his disposal ahead of the visit to London Road, with Ben Davies still unavailable for selection.

Williams and his team mate Nathaniel Phillips were identified as potential targets when Heckingbottom, who signed goalkeeper Adam Davies on a short-term contract earlier this week, discovered his recruitment budget would only cover a loan. With Phillips attracting interest from the Premier League, United’s coaching staff viewed Williams as the more realistic of the two before learning Jurgen Klopp is minded to retain the 20-year-old if Phillips does depart.

Although other lines of enquiry are being explored, Heckingbottom wants officials in the North-West to keep him up to date on Klopp’s plans after warning the race for the top six could go “right down to the wire.”

“We’ve got so many games we could finish anywhere,” said Heckingbottom. “That’s why we are focusing on what we are doing. Just game after game. That’s got to be the approach.

“What’s making it strange is the big discrepancy in the number of games people have played.

“Ultimately it will come down to points. If we stay on this this run then we will be there or thereabouts. I think it will go right to the wire.”

After suffering a spate of postponements over the Christmas and New Year period, United prepared for their visit to London Road eight points behind sixth-placed Huddersfield Town but having played three games fewer than Carlos Corberan’s side. That is now four after Town faced Stoke City, Davies’ former club, last night.

However, with only 16 outfield players able to take part in Thursday’s training session, Heckingbottom fears United’s squad could be placed under intolerable pressure unless further reinforcements are brought in.

“Ideally, we want to try and keep a freshness there,” he said. “That could be important.”