When Scottish football resumed after the World Cup, Celtic were not at their best, only prevailing by one-goal margins in their opening two games and then needing to battle their way to a 2-2 draw with Rangers.
However, in their four matches since the Old Firm derby, all of which have taken place at their home ground, Celtic have scored 13 goals without reply.
Although they have faced no team higher than seventh-placed St Mirren, Ange Postecoglou can only have been left impressed by the improvements made by his team.
In total, the Bhoys are on a 12-match unbeaten streak in all competitions, and a 15-match run when only including fixtures in the top flight.
On Sunday, they also return to Tannadice for the first time since they thrashed their hosts by a 9-0 scoreline at the end of August.
Two days later, Liam Fox was promoted to the role of head coach after the sacking of Jack Ross, and the decision was quickly made to hand him the reins on a permanent basis.
Fox has since delivered seven wins and eight defeats in 19 matches, their best form over a prolonged period occurring since November 9.
Eleven points have been collected from the most recent eight fixtures in the league, leaving the Terrors three points above bottom spot.
Since the resumption, Dundee United have only suffered one defeat, that coming at home to Rangers, and they progressed in the Scottish Cup last time out as they beat Stirling University by a 3-0 scoreline.
Having rung the changes for the Scottish Cup tie, Fox is expected to revert back to a similar side which lined up for the 2-2 draw at Hibs before that fixture.
Although Charlie Mulgrew was able to get a welcome 90 minutes in his legs after a spell on the sidelines, the 36-year-old will likely only be named among the replacements.
Playmaker Glenn Middleton heads into this fixture having netted in successive matches.Celtic boss Postecoglou went stronger than expected for the Scottish Cup tie with Greenock Morton, but changes will be made for this fixture.
Matt O’Riley, Reo Hatate and Jota should all come back into the starting lineup, while recent signing Yuki Kobayashi is in line for a third straight start at centre-back.