Scott McDonald (second from right) got the winner at Tannadice
Dundee United edged out Greenock Morton to go second in the Scottish Championship in a game that really only came to life in the second half.
James Keatings and Scott McDonald both scored their third goals of the season to keep Ray McKinnon's men in touch with Dunfermline at the top.
Bob McHugh briefly brought Morton level but they could not find a second goal.
The gap at the top sits at two points but St Mirren could return to within a point of the leaders on Sunday.
The Buddies host Queen of the South.
Paul McMullan, Fraser Fyvie and Keatings all had to resort to long-range efforts before McMullan picked out Keatings with a terrific 34th minute pass and the striker's header brought a great one-handed save from Morton keeper Derek Gaston.
Morton were content to hit on the break and chances were few and far between, although Ross Forbes did flash the ball just past the post to give the away fans some hope.
The game was crying out for a goal and it came midway through the second half when McMullan's pass into the box found Keatings and he dispatched a good left-foot shot past Gaston.
Morton got back in the game when Forbes crossed deep into the box for Robert Thomson to lay the ball back and substitute McHugh prodded in his fifth goal of the season past Harry Lewis.
At that stage it looked like either side could win it, but it was United who got the winner when McDonald was in the right spot at the right time to nick the ball home after Mark Durnan's powerful header had crashed back to the former Celtic and Motherwell man off the post.
The home fans in the 4,569-crowd who had been restless at half-time, cheered their side to the rafters at the end as they set up a very tasty trip to Dunfermline next week.
Post-match reaction
Dundee United manager Ray McKinnon: "I was delighted with the three points, Morton are a good side, with a good manager and good players. We saw the improvement that's been coming, we created a lot of chances and it was a deserved victory. The really positive thing was the performance.
"You have to be patient, you have to make sure you keep the ball in the final third. It's easier to defend than open up in attack. The boys looked very dangerous today. They stuck at it and showed quality in the final third.
"It's taken us a long time to get [Scott McDonald and James Keatings] on the park together. Scott's performance was excellent, there's improvement to come from James, but potentially there's a very good strike partnership there."
Morton manager Jim Duffy: "We put an enormous amount of work into the game. It's a tough venue, but the commitment was magnificent. They never gave in at any stage. We're bitterly disappointed we didn't come away with something. We made a couple of crucial errors and Dundee United capitalised on that.
"Dundee Untied will be hot favourites for the league, and probably rightly so. From our point of view, we competed really well with them, we made it tough for them.
"We didn't just sit in and hope for the best. We had opportunities. The players were adamant there was a handball in the last action of the game, but I couldn't see it from where we were in the dugout. Players will claim for everything, but in the dressing room they were adamant."
