Jim Jefferies worked with Grant Murray at Tynecastle

The 30-year-old impressed in training despite missing Tuesday's 2-2 draw with Queen of the South.

Murray, who rejected a new contract with Thistle, played under Killie boss Jim Jefferies at Tynecastle.

Jefferies said: "He is a great lad who is fit and can do a good job for us. He's aware our defence did well last season and we can't guarantee a place."

Murray helped Thistle win promotion to the First Division last season and they were desperate for him to remain at Firhill.

"He had the opportunity to stay at Partick and I told him he should take it because he would be guaranteed regular first-team football there," said Jefferies.

It's up to me to fight my way into the team here Grant Murray

"But it shows you the ambition and determination he has that he is willing to battle for a place in the team. That is the type of player we want here.

"He knows he is coming here as a squad player, but he also knows, if he does enough to break into the first team, he will stay there.

"And the one thing you're guaranteed with Grant is that he will always give you 100%."

Murray became a first-team regular during six years with Hearts before moving to St Johnstone in 2001.

He moved on to Firhill in 2003 but could not prevent the Glasgow club slipping out of the Scottish Premier League then down to Division Two.

Now, after becoming Killie's first summer signing, he was relishing another chance to prove himself in the top flight.

"I had spoken to a couple of teams," he said. "But, when I knew Kilmarnock were interested, I was focused on that and I'm glad it's gone through.

"I've worked under Jim before and he knows what I'm like as a player, so hopefully that has helped in bringing me here.

"I've also played in the SPL with St Johnstone and Partick, so it's up to me to fight my way into the team here."

Meanwhile, Jefferies will make a decision on two more trialists, midfielder Keith Lasley and defender Trent McClenachan, over the weekend.

Australian 21-year-old McClenachan played 34 times last season on loan from West Ham United as MK Dons were relegated from England's League One.

Lasley, 26, spent five seasons with Motherwell before moving to Plymouth Argyle in 2004.

But he failed to become a first-team regular with the Championship outfit and spent time on loan to Blackpool last season.