Callum Hendry's introduction provided a spark for Tommy Wright's side in a game of few chances.

The forward burst into the box to square for Ali McCann, who tapped home the Perth side's first shot on target.

It was a fourth clean sheet in a row for St Johnstone, while Hamilton remain 11th.

Goalkeeper Zander Clark was a spectator for the majority of his 100th St Johnstone appearance, and counterpart Luke Southwood also had a quiet afternoon, until the introduction of Hendry.

The win means Wright's side are unbeaten in four.

• Reaction & how it happened

A game to forget

In the first half, two hard-working, well-drilled, well-organised teams did a pretty good job of cancelling each other out.

Hamilton nil, St Johnstone nil, meaningful efforts on target nil, proper saves from either goalkeeper nil, flowing football nil, reasons to forsake the high street Boxing Day sales nil.

You get the drift. The first 45 minutes were not good. At all. Meaning that things could only improve, right?

We had to wait an hour for the first flash of proper quality. Mickel Miller darted forward from midfield, leaving a couple of St Johnstone players trailing in his wake.

The only thing that could stop the Englishman, just outside the box? A crude foul from Murray Davidson which rightly earned the veteran midfielder the game's first yellow card.

The match then reverted to type when, from a very promising position about 20 yards, Will Collar's free-kick blasted into the middle of the defensive wall.

A few minutes later, Miller had Clark scrambling to keep it goalless. Nothing to do with the shot, really, more the wicked spin gained from a huge deflection. The slide from the keeper prevented the corner.

With a quarter of the game left, both managers had seen enough. Steve Davies came on for Accies, Drey Wright came on for St Johnstone, and the ball was soon in the net.

Unfortunately for the visitors, so was the home goalkeeper Southwood, bundled over the line by Chris Kane. No goal. No surprise. No change to the stalemate.

Another substitution. Hendry replacing Stevie May for St Johnstone. He had an instant impact, his hook-shot on the turn appearing to hit an Accies arm as it was deflected away from goal, with loud claims for a penalty ignored by referee Gavin Duncan.

Fans of the Perth club will remember the effect Hendry had when he came on in the last meeting between these two sides at the end of October - his late goal gave them their first league win of the season.

They would have that winning feeling over Accies again. Some poor home defending allowed their opponents to gather just outside the area, and when the ball was cut back, McCann arrived to smack it past Southwood and send the small band of away fans behind the goal away happy.

Man of the match - Ali McCann

The perfect time for the 20-year-old to register his first St Johnstone goal. The strike could prove invaluable, with the Perth side now seven points clear of Hearts and unbeaten in their last four matches.

He didn't really have any other serious rivals for the award, with the possible exception of the industrious Miller for Hamilton, so McCann's solid midfield display earns him the prize.

'We had our pockets picked' - reaction

Hamilton head coach Brian Rice: "I thought first half we were excellent - probably as well as we have played at home. I thought we had our pockets picked, and fair play to them for taking the three points.

"I thought we were the better team by a distance. I don't think we tested the goalkeeper enough, but I can't ask for any more from the boys, except for in the final third having more attempts at goal."

St Johnstone manager Tommy Wright: "I'm really pleased we came here and gave them few opportunities. I thought we looked the more threatening side in a game of very few chances.

"That's four clean sheets in a row - that's been the basis of staying unbeaten. When you consider the horrible start we had the players deserve a lot of credit for turning that around."