South Africa fast bowler Dale Steyn has soared towards the top of the world rankings in the last year and is relishing the prospect of facing England and Australia over the next few months.

"I have done well but we are coming up against two big teams of world cricket who will be difficult to knock over," Steyn told Reuters in an interview ahead of the first match of their England tour in Somerset on Sunday.

"They are big challenges but I like challenges."

Steyn, who sampled English conditions with Essex in 2005 and Warwickshire last season, is due to face the world's top-ranked side at the end of the year.

"We are in England now, then we go to Australia after the Champions Trophy (in Pakistan) and Bangladesh at home so this is a time where I have to stand up and be counted," he said.

Steyn was 31st in the test bowling rankings a year ago but is now second after briefly holding top place ahead of Sri Lanka spinner Muttiah Muralitharan.

It demonstrates the success he has enjoyed since South Africa's tour to Pakistan in October, a spell in which he has claimed 78 wickets in 12 tests to make it a total of 120 in 23 matches.

"It's all happened quickly but although I have had a fantastic season I know I have to continue this throughout my career to be considered a world great," Steyn said.

"It was fantastic to be rated number one but my average and number of wickets over an extended period, when I retire, is more important to me. Consistency is a big thing."

Steyn, who turned 25 on Friday, said he was trying to combine the sort of accuracy and movement Shaun Pollock used to display with the searing pace of Allan Donald.

TEST DEBUT

The paceman showed evidence of this on his test debut in December 2004 when he bowled England captain Michael Vaughan, who shaped to play towards mid-on only to lose his off stump after the ball swung late and left him.

Steyn is well aware of the qualities that set him apart.

"Everybody can bowl at 135kph and put it in the right areas. You can get a school kid to do that," he said.

"But anyone who can run in and bowl at 150kph (90mph) is something special, especially if you can swing the ball at the same time. Pace is definitely my biggest weapon but pace combined with swing is deadly."

England beat visiting New Zealand 2-0 in their recent test series though the home team's batsmen were rarely tested against an under-strength side devoid of the fastest Kiwi bowler, Shane Bond.

South Africa will be a bigger test.

"We have a few guys who can bowl fast and swing it, like Makhaya (Ntini) and Morne Morkel," Steyn said.

"It's important to me I am always outwitting the guy next to me . because it raises the bar all the time. It's healthy competition within the team.

"The more they are pushing the better I have to become so it doesn't allow you to relax. It means I am always fighting for a spot."