Livingston racked up a fifth consecutive victory in all competitions thanks to a second-half strike from Aaron Taylor-Sinclair.
The defender's second-half header secured the Lions, who were dominant from start to finish, a 1-0 victory over third-placed Motherwell.
An out-of-sorts Well had keeper Mark Gillespie to thank for keeping the home side at bay for much of the match.
But, following league successes against Hibernian, St Johnstone and Hamilton, and a Scottish Cup win against Raith Rovers, Livi were not to be denied.
The West Lothian outfit bossed proceedings from the off and carved out all the first-half opportunities.
Lyndon Dykes was the first to threaten after just five minutes when his shot was beaten away by Gillespie.
It was the first of a string of saves the visiting keeper was forced to make before the interval.
With 13 minutes on the clock, a cross from Ciaron Brown was headed back by defensive partner Jon Guthrie but Gillespie dived to his right to turn round Dykes' flick.
A minute later, Livi should have been ahead. Craig Sibbald won possession inside the Motherwell half and slipped in Scott Pittman but the midfielder's low shot was repelled by Gillespie's legs.
The Englishman was single-handedly keeping Livingston at bay and was at it again midway through the half when he did well to push away a low Jack McMillan cross.
With Pittman and Scott Robinson bringing out further saves from Gillespie with drives from just outside the box, it was a wonder how Livingston had not yet made the breakthrough.
It was a theme that continued as the half-time whistle approached.
First, Guthrie volleyed over from a Sibbald corner and then another low centre from overlapping full-back McMillan had to be turned past by the hard-pressed Well defence.
Well manager Stephen Robinson reacted at half-time by changing his personnel, with the introduction of defender Bevis Mugabi and striker Christy Manzinga for Christian Ilic and Jermaine Hylton, and his formation from a 4-3-3 to a 3-5-2.
It gave Well a brief boost but the chances started coming again for Livingston.
Pittman's cross ricocheted off Scott Robinson's head and drifted over before Dykes' shot from a low Sibbald free-kick was deflected wide.
When Gillespie blocked from Marvin Bartley it was clear the home team were building a head of steam again and they finally found the breakthrough in the 68th minute.
Brown's long throw from the left flicked off the head of a home defender and a determined Taylor-Sinclair nodded into the top corner from close range at the back post.
A neat passing move released Dykes into space 11 minutes from time but his low shot was touched round the post as Livi sought the clinching second.
And they almost needed it when skipper Peter Hartley nearly grabbed an unlikely equaliser for Motherwell in injury-time with a bouncing effort that crashed back off the post.
