Dundee United manager Jim Goodwin "firmly" believes Kilmarnock's winning goal should not have stood after his side lost 1-0 at Rugby Park.

Marley Watkins' controversial header gave Kilmarnock victory and moved Derek McInnes' side to within three points of the Scottish Premiership's top six.

United players appealed for a foul after Watkins collided heavily with goalkeeper Jack Walton as they challenged for a high ball in the six-yard box on 72 minutes, but the goal stood following a VAR review.

Goodwin's visitors were further incensed at the death when they were denied a penalty after the ball hit Corrie Ndaba's hand from a cross.

"The major disappointment for us is the goal that we concede," Goodwin told BBC Scotland.

"VAR is there to help in those situations. The centre-forward for Kilmarnock has his arm right across Jack Walton's face, making it impossible for Jack to get off the ground to try and catch the ball. I firmly believe that that goal should've been ruled out."

Kilmarnock boss Derek McInnes commented: "It's a mistake, maybe, from the goalkeeper. Marley uses his experience and just becomes a nuisance and gets the goal."

In a game of few openings, United debutant Allan Campbell and the hosts' Joe Wright had the best sights of goal in the first half.

Then Premiership top scorer Sam Dalby drew a fine save from Kilmarnock's Kieran O'Hara in the second, before United's Ryan Strain headed over.

Kilmarnock climb two places to ninth, while third-placed United remain two points above Aberdeen.

Campbell had an early chance following a throw-in but could not direct his effort on target, similar to a longer-range shot by team-mate Emmanuel Adegboyega later.

Wright was first to threaten for Kilmarnock, his volleyed effort kept out by Walton.

Early in the second period, Luca Stephenson led a three on two situation for United but his pass was short and cut out.

Dalby almost broke the impasse when his head connected with Will Ferry's long throw, O'Hara touching the effort on to the crossbar before Kilmarnock cleared.

Watkins got the vital touch after Declan Gallagher cleared Fraser Murray's cross high into the air and the hosts got the verdict they were looking for on review.

The visitors should have levelled when Strain met Ferry's excellent cross and nodded over, with Dalby just behind and probably in a better position to score.

And United substitute Glenn Middleton got his footing wrong as he fired the ball across the face of goal as time ran out.

After last season's top-six finish, Kilmarnock appeared to be in a fairly lowly position in 11th prior to this.

But a closer look at the points gap showed it would only take one positive result to alter that picture.

And so it proved, with Derek McInnes' side overtaking Ross County and Dundee and gaining ground on St Mirren.

Kilmarnock were similarly stout to United, recognising their visitors' prowess at set plays and deliveries in towards the predatory Dalby.

After three narrow defeats in all competitions last month, the Watkins goal meant February opened with a welcome change of fortune for McInnes' men and a repetition of last season's top-six finish is very much on.

United's lofty status, eight months on from promotion, belies their recent form with six points from a possible 18 registered since the turn of the year and three defeats in a row in all competitions.

However, that run betters nearest challengers Aberdeen's recent form, with the Pittodrie men without a league win since November.

Former Motherwell man Campbell's addition in midfield brings experience and Premiership nous and can only help Goodwin's team emulate Hearts' feat of following promotion with a third-placed finish three seasons ago.

The Tangerines may feel VAR just was not smiling on them in Ayrshire, with a late penalty claim for handball against Ndaba not moving the officials to act.

Kilmarnock manager Derek McInnes: "Dundee United were better than us first half. Sometimes, you've just got to persevere and stay in the game. The one thing we did stand up to today is Dundee United's long throws and set plays. They're a huge team, they've got real weapons with that ball going in your box all the time. So, we had to defend that.

"We've played better in recent weeks and even this season and not won games. It's great we get our clean sheet. The win, the three points is terrific for us."

Dundee United manager Jim Goodwin: "I don't think it was a game that we deserved to lose over the balance of play. The game was really scrappy. It was two strong teams battling it out.

"I thought we had more opportunities than Kilmarnock, I thought we got into more dangerous areas. The bit that was lacking was that final ball at times. We were unfortunate at 0-0 with the Sam Dalby header that comes crashing back off the bar."