Tannadice was packed out by 11,062 expectant fans, most in tangerine, but the first half lacked quality with only a couple of chances created and missed.
The game livened up a bit after the break before descending back into a mostly dull contest which produced little excitement.
Both sets of fans will look for more from their respective teams when they meet again in the second leg in Paisley on Sunday.
However, it will be Oran Kearney's Buddies, who finished 11th in the top flight, and who are now unbeaten in seven matches, who will fancy their chances of finishing the job and retaining their Premiership status.
The Taysiders went into the game unchanged following their encouraging 3-0 win over Inverness on Friday night which sealed an aggregate play-off semi-final victory.
Saints, cheered by over 1,000 travelling fans, had defenders Lee Hodson and Gary MacKenzie and striker Cody Cooke, who scored hat-trick as a substitute in the 3-2 win against Dundee at Dens Park at the weekend, back in the side.
United threatened early when Ian Harkes took a clever pass from Paul McMullan and fired in a drive which was blocked by visiting midfielder Ryan Flynn for a corner which came to nothing.
Set-pieces appeared to offer the biggest threat from the Paisley side.
In the 15th minute United skipper Mark Reynolds was relieved to see his wayward header from Kyle McAllister's whipped-in free-kick saved by his own keeper Benjamin Siegrist.
Moments later, at the other end, McMullan raced on to a long clearance from Nicky Clark but under pressure from chasing defender Mihai Popescu he drove straight at keeper Vaclav Hladky.
United keeper Siegrist had the best and most spectacular save of the first half just before the break when he threw himself high to his right to palm away a curling effort from McAllister.
The Tannadice number one also started the second half by making great save at point-blank range from a Kyle Magennis effort, after Hodson had headed back a deep cross from Flynn.
The Terrors responded and McMullan flashed two dangerous deliveries across St Mirren's six-yard box but found no takers.
With his side struggling to get the breakthrough, United boss Robbie Neilson threw on all three substitutes – Pavol Safranko, Sam Stanton and Callum Booth – but to no avail as the game petered out, to be resumed in Paisley.