With all the technology now used to analyse cricket it's amazing that anything remains a mystery, but it appears no amount of slow-motion replays and computer programmes can help batsmen unravel the skills of Ajantha Mendis. Another magical spell, this time of 3 for 9, ended a promising start to New Zealand's run-chase even though Daniel Vettori was adamant his players knew what was coming at them.

Mendis' crucial impact came in his second over - the ninth of the innings - when he lured Ross Taylor into an ugly heave across the line and then beat Scott Styris' prod with one that held its line. He later returned to remove Peter McGlashan and didn't concede a boundary in his three overs - such was Sri Lanka's dominance he didn't have to bowl his full quota. Each time Kumar Sangakkara's team has been tested in this tournament, it has had the bowling to withstand the pressure.

It left Vettori in phlegmatic mood after a tournament where their batting failed to fire. "I think we played the first six overs pretty well and I was fairly happy with our position," he said. "Unfortunately, which makes it tough, a lot of guys picked Mendis today, but he still bowled so well that it was difficult to score from him and you saw the turn he got which made it even harder. We can sit here and blame our players - and we will work hard on our reviews - but you still have to admire the quality of bowling on display."

Mendis has been on the international scene for a year after making his debut in West Indies and the library of footage of him flicking his carrom ball and varying his pace is growing. That, though, has been of little help to the growing list of batsmen who have been left looking a little foolish.

"The guys picked him, I don't think he's a mystery bowler just a very good bowler," Vettori added. "It's the same with [Muttiah] Muralitharan. Over the years guys have been able to decipher what he bowls but he's still so good that it's difficult. It's the same with a number of bowlers around the world - once you've picked them it's a great thing, but if they're still good enough to beat then it's very tough."

And it isn't just opposition batsmen who are left befuddled. Even Mendis' team-mates, which include some of the best players of spin in the world, have been left floundering during net sessions. "He still gets us sometimes," Mahela Jayawardene said with a smile. "Too many things come out of his fingers so it's very difficult to keep track of it. He's something special, but the important thing is he has maintained his dignity. He's got great support from Murali and it's an ideal atmosphere for a young spinner to come through."

To make life even tougher for New Zealand it wasn't only Mendis they had to contend with, but also the experience of Muralitharan and the ever-increasing variety produced by Lasith Malinga. Although they welcomed back Ross Taylor - albeit not 100% fit after his hamstring injury - and were boosted by the availability of Brendon McCullum, Sri Lanka always held that X-factor.

Vettori was honest enough to admit that the batting had struggled badly with the highest score against a major team being their 127 at Lord's, when they lost to South Africa by one run. Only against Scotland, when they knocked off 90 in six overs, and against Ireland where they racked up 198 has the order come close to its potential.

"It has been difficult, but we have been lucky with a fortunate draw which meant we could win just two games before today against Associate teams and still have a chance of making the semi-finals. In a lot of a ways that probably wasn't right." Vettori said. "We were at full strength [today] apart from Jesse and, we still had the opportunity today to turn up and win the game so we are devastated.

"For a group of guys who had such high expectations, especially of our batting order, our highest score was about 120 and that's just not good enough."

Sri Lanka have no such concerns with their form. They have scored the runs required and even totals that haven't appeared too daunting grow in value when placed alongside the attack that will defend them.

"We have a very good bowling attack and if our batsmen back themselves to get the runs on the board or chase them down I'm confident we can go all the way," Jayawardene said, while cautioning that the job wasn't done. "We set ourselves goals coming into the tournament and now we have two more goals. We just need to stay calm and try and get another win to get into the final."

With the form they have shown it will take a commanding performance to bring them down and a batsman to master the international man of mystery. But ominously for anyone who feels they can conquer Mendis, there was a promise of more to come as Jayawardene translated for his team-mate. "He feels because batsmen aren't familiar with him he'll stick to what he does, but he has a few plans up his sleeve." The tricks he already has are working just fine at the moment.