By the adage that successful promotion campaigns are often built on a capacity to win ugly, the first half of the footballing Christmas has been happy for Sheffield United.

This was a victory "dug out" in the truest sense of the phrase because impressive and pretty it certainly was not.

Jack Lester's penalty early in the second half - in off goalkeeper Gavin Ward's hands - was a suitably scruffy way to decide an unpalatable game. Other than a frenzied late onslaught in search of an equaliser, there was more fun scouring discarded crackers for jokes.

Not that the Sheffield United manager, Neil Warnock, will be complaining. His side edged closer to the top after ending a mini-Coventry revival that had accounted for then leaders West Brom last weekend.

"It does help when you can defend from the front as we did today," Warnock said. "We won't have any more difficult away games than at Coventry and if we play like that we should win a lot more on the road."

Warnock despatched coaches David Kelly and Tony Daley to that game in the wake of the postponement at Derby. The duo left before Johnnie Jackson hit the last-gasp winner against Albion and the scorer has since departed, too, recalled in a hurry off his loan from Tottenham.

The Sky Blues team the midfielder said farewell to were disappointing. The onus is usually on the home side to dictate but they cranked up the pressure only in the dying minutes, when the referee turned down two penalty appeals and so earned himself an escort from the field and some distinctly un-festive comments.

Eric Black's two previous matches as caretaker manager had been won and Gary McAllister's attendance for the first time since being granted compassionate leave was more a paternal gesture - his son was mascot for the day - than a signal that his return to work is imminent.

How an error-strewn, often featureless encounter needed him on the pitch, though, rather than up in the stand.

These two clubs have used no fewer than eight goalkeepers between them this season but they could almost have managed without one here.

Sheffield United's 2003 Player of the Year Paddy Kenny returned from a four-month absence with knee trouble and was 93 minutes into his comeback game before called upon to make a save - from Mo Konjic's bouncing header to a Steve Staunton corner.

The goalkeeper could have done without the sight of his former Blades team-mate Patrick Suffo bearing down on him twice in the opening minutes. But the striker fired high or wide or both.

The Cameroon international somehow became even more wayward as the game wore on. One first-half shot with his left foot missed the corner flag by five yards and bounced out for a throw-in. Then he tried his luck with his right and put a volley in the top tier of the Ace Resources Stand.

If this was an accurate vision of life without Michael Brown, there was plenty for Blades fans to fret about. The midfielder is confidently expected to join Tottenham for £500,000 when the transfer window opens next week and there was not much creativity in his absence at the start of a four-match suspension.

Sheffield United did hit the outside of the post through Peter Ndlovu in injury-time and what they did well enough was defend, especially once they had established some daylight with Lester's seventh League goal of the season.

The striker was fouled by Konjic as he turned well on to Ashley Ward's short pass and picked himself up to score the latest in a series of in-off penalties.

Goal: Lester pen 0-1 (56).

Coventry City (4-4-2): Ward; Whing, Davenport, Konjic, Staunton; Mansouri, Safri, Doyle, Warnock (Adebola, 60); Suffo (Morrell, 77), Joachim. Substitutes not used: Shearer, Shaw, Pead.

Sheffield United (4-4-2): Kenny; Kozluk, Jagielka, Page, Wright; Ndlovu, Montgomery, McCall (Rankine, 71), Tonge; Lester (Whitlow, 90), Ward (Allison, 79). Substitutes not used: Peschisolido, Kabba.

Referee: C Penton.

Bookings: Coventry: Doyle, Konjic. Sheffield United: Ward, Montgomery.

Attendance: 21,132.

Man of the match: Phil Jagielka.