GLASGOW (AFP) - Rangers manager Walter Smith is convinced French striker Jean-Claude Darcheville can help his side wrestle the Scottish Premier League title from arch rivals Celtic.

The Ibrox club opened up a four-point lead at the top of the table after Darcheville's last-minute goal earned a 1-0 win at Inverness CT on Sunday.

Darcheville's volley clinched a sixth win in their last seven league matches and re-established a significant advantage over reigning champions Celtic.

Now Smith just wants to find a way to keep the former Bordeaux star in peak condition.

"He obviously has a little bit of match practice still to get, but I feel he will be a very important player for us this season," Smith said.

"Maybe we were asking Jean-Claude to do too much in terms of physical work in training and we have cut that back a little bit.

"Our main objective is to keep him injury free so the physios and sports scientists are working hard to make sure that happens as much as possible during the second half of the season."

Inverness boss Craig Brewster added: "I thought the game had 0-0 written all over it and then we lost the goal in the 89th minute."

For a long time it looked as though Rangers would be frustrated.

After a scrappy start Inverness forced the pace impressively. They had the first serious attack which ended with Marius Niculae sending an ambitious volley over the top of Allan McGregor's crossbar.

McGregor had to race from his line and halt a Markus Paatelainen surge after the Finn had done well to control a pass from Richard Hastings.

It was another intervention from Rangers keeper McGregor that kept Inverness at bay when he scrambled to save after Carlos Cuellar nearly put through his own goal.

Rangers finally came to life thanks to Chris Burke. The winger whipped over a cross to Daniel Cousin and his header was well saved by Michael Fraser.

The visitors went even closer three minutes before half-time. Steven Naismith fed a pass to Steven Whittaker and the right-back advancing before forcing Fraser into a fine stop to keep out his low shot.

Darcheville replaced Naismith at the break as Smith tried to revitalise his lethargic outfit.

The move was to prove inspired. The Frenchman helped raise the tempo with an incisive run after collecting Charlie Adam's well-measured pass. Although his shot flashed over Rangers were starting to look more dangerous.

Smith's side dominated possession from then on, although they were nearly caught by a sucker punch when Niculae drove in a long-range effort that McGregor managed to push away.

Adam responded with a fierce drive from 25 yards that cannoned off the crossbar. Adam had the ball in the net from a narrow angle but the effort was ruled out after Cousin was adjudged to have strayed offside.

Rangers had no need to rue that decision for long. In the 89th minute Darcheville steered home from close range to finally end Inverness's stubborn defiance.