Saracens and Samoan prop Cencus Johnston has set his sights on being the best tight head in world rugby - and he's well on the way according to Director of Rugby Alan Gaffney.

The 26-year-old Samoan powerhouse, contracted to Saracens until 2011, demonstrated his destructive running ability in yesterday's 24-20 victory over Sale Sharks at Vicarage Road, when collecting the ball 22 metres out to step inside the Sharks defence and carry three of them over the line.

It was a try which even left Sharks Director of Rugby Phillipe Saint-Andre scratching his head after the game, but it's something which comes naturally to the 21st (135kg) prop.

"Running with the ball has always been a natural part of my game and I love it," he explained.

"When I joined Saracens, I sat down with Alan Gaffney and Eddie Jones at the time and we set out a number of goals and one of those was to be up there with the best in world rugby. Having played in the NPC in New Zealand, I've always looked up to Carl Hayman and thought to myself there is no reason why I can't be like him. I realise I still need to add a few extra dimensions to my game but I'm working hard with the coaches on those areas."

And Gaffney added that he believes Johnston is capable of reaching his goal.

"There's no doubt that he has the potential to be the best tight head prop in the world. He has the ability of doing things as a tight head that very few in the world can. The try he scored on Sunday demonstrated the great acceleration he has for the size of him, and while there are still a number of areas he has to improve on, the Guinness Premiership is definitely bringing out the best in him."

Johnston admits that the scrum is an area of his game that needs improvement, but he's already seeing the benefit of working with Cobus Visagie and Forwards Coach Adrian Kennedy.

"Playing in England has really helped in terms of the scrum and the set piece in general because it's a huge part of the game," he explained. "Cobus and Adrian have worked very hard with me and I'm really grateful for that. I know it must be particularly hard for Cobus because I've been keeping him out of the team, but he is very supportive of me and he's a player I rate very highly.

"I've also worked a lot with the coaches in recent weeks to improve my body position in contact and also trying to beat the first defender and that has helped a great deal."

He didn't beat just one defender on Sunday; instead he left three in his wake and carried another three over the try line and that helped him be named man of the match.

"I don't really remember much about the try," he added. "I was actually down on the floor waiting for some treatment and I saw Chris Jack running towards me and thought I'd better get up quick! I got the ball and just went for the line."