St Helens avenged their Challenge Cup semi-final defeat and moved to within 80 minutes of a fourth successive Grand Final appearance with a patchy Super League play-off win over Huddersfield.

Four defeats in their last five matches, including that cup exit at the hands of the Giants, had threatened to wreck Saints' season but they never looked back after scoring three tries in the first 21 minutes.

Their reward is a week off and a home semi-final while Huddersfield, who were without five members of their Wembley line-up, will have another chance to gain a first play-off win with a home tie in next week's preliminary semi-finals.

After their early lapses, the Giants demonstrated why they have the best defence in Super League but they met their match tonight and failed to score a try for the first time for 14 months.

Saints were still well below their best but they received the encouragement of a gift try after only two minutes and were 14-2 ahead before the visitors began to get into the game.

There were shades of Huddersfield's disastrous start to the Challenge Cup final when Saints' strong-running prop Tony Puletua intercepted a sloppy pass from Liam Fulton and he proved unstoppable 20 metres out from the line.

The Giants' inspirational skipper Brett Hodgson pulled two points back with a penalty but Saints extended their lead on 13 minutes when stand-off Leon Pryce's trademark jinking run took him all the way to the line.

Huddersfield struggled to make any headway in the game and it was no surprise when Saints went in for a third try, fanning the ball the full width of the pitch for the dangerous Kyle Eastmond to get winger Francis Meli over at the corner.

Eastmond was able to convert just one of the tries but, at 14-2, the home side were in full control.

The Giants ought to have made more of their first meaningful attack when towering prop Eorl Crabtree was put through a gap by the scheming Hodgson but Saints full-back Paul Wellens produced a superb last-ditch tackle to deny the big man what would have been his first try of the season.

Centre Stephen Wild also lost the ball with the line at his mercy as the visitors found their touch to give their supporters something to cheer.

They had their moments in the second half, too, with prop Danny Sculthorpe releasing Fulton into space but the Saints defence held firm.

Saints thought they had scored again when right winger Ade Gardner won the race to Sean Long's kick to the corner but slow-motion replays revealed a knock-on and the only score in the final hour was a 72nd-minute drop goal from Long.