The New Zealand striker scored his first competitive goal for almost two years during Sunday's Clydesdale Bank Premier League win over Hearts at Parkhead and is set to lead the line in tonight's Co-Operative Insurance Cup third-round tie at Falkirk.

However, when the former Hibernian striker was sent on loan to Norwich in January it looked like was on his way out of Parkhead permanently.

A knee injury cut short his stay in Norfolk and brought an end to his season under former Hoops manager Gordon Strachan.

Killen, 27, spent the summer in rehabilitation to give himself a chance under new boss Tony Mowbray, and part of that process took place during a trip to South Africa with the New Zealand national team where they trained against an unusual backdrop.

"New Zealand took the national team players to a safari camp in South Africa to prepare us for the World Cup qualifiers and that was great for me," Killen said.

"I knew I couldn't afford to take the summer off and not train because I'd missed too much playing time due to a knee operation that wrecked my stay on loan at Norwich City.

"I wanted to be sharp when pre-season training began with Celtic and I found myself training in the middle of nowhere with rhinos and elephants for company.

"My contract expires at the end of the season but I won't be shouting about wanting a new deal.

"I need to earn the right to a new agreement.

"That means I need game time and goals for Celtic.

"I'd love to stay because I think it's brilliant at a club like Celtic."

In a live radio interview immediately after the win over Hearts, Mowbray, in his excitement, let slip an expletive when praising Killen for his attitude.

The Hoops striker is looking to impress his manager once again at the Falkirk Stadium.

He said: "It's tough when you are coming on for 10 or 15 minutes here and there.

"You have to make a massive impact to try and get your jersey.

"So starts are important for all players, me especially.

"Sunday was a good day all round. We got the result, which was the main thing, and, from a personal point of view, it was great to score at home.

"I want to be playing week in, week out and, if I carry on scoring goals, there's no reason why I shouldn't be playing but it does come down to the manager.

"But it's obviously nice to have the backing of the manager, he knows what I can do and that gives you the confidence."

The cup tie may be seen as a welcome break from the SPL for bottom side Falkirk but manager Eddie May claims there is no more or less pressure on his team just because there are no points at stake.

"You still need to go and win a football game," May said. "It's not any easier because you are not playing for points, you are still playing for the big prize of winning a game.

"We just have to make sure we play to the standard we are capable of. If it's good enough at the end of the night, great. If it's not then we'll assess it."