The phrase "quietly confident" captures New Zealand's approach to almost any international assignment, and Brendon McCullum used it again ahead of their Champions Trophy opener.

On the surface, there is perhaps no reason to be so quiet about it. They have just felled the hosts, England, in a three-match series, have an opener in incredible form, and even without Daniel Vettori - who is doubtful for the match - possess an attack capable of troubling any top order.

Only they are up against an opposition that has mauled them almost without relent, in the last five years. In the last 11 completed ODI matches between the two sides, Sri Lanka have won 10. From Hamilton to Hambantota, Mumbai to Kingston, most matches haven't even been close. New Zealand might take some solace that the only victory in that lot came in the previous Champions Trophy, on a fast Johannesburg pitch, but both captains expect spin to play a major role in the match, and in that regard, Sri Lanka hold the advantage.

"Sri Lanka has obviously dominated us in recent history," McCullum said. "But the wickets that we played on back in Sri Lanka in the last series will be a lot different than what we're expecting over here. They've got some mystery spinners and some obvious quirks about their bowling line up. They've also got some experienced batters and are a tough proposition. Our approach is very much on making sure that we play as well as what we have in the last few games in this form of the game."

Sachithra Senanayake is likely to be Sri Lanka's frontline spinner, though, and despite Senanayake's relative freshness at the top level, McCullum knows more about him than most. Senanayake was a big buy for McCullum's Kolkata Knight Riders IPL franchise in 2013, and the New Zealand captain suggested that insider-knowledge might give his side the edge.

"Sachi, he's a different proposition to Murali," McCullum said. "His bowling is definitely one of the mystery spinners that come around, and he's got a good variety of different balls which he bowls as well, If we give him a sniff or show some frailty to such spinners such as Sachi, he could quite easily expose us. But I hope we play him with some freedom, and hopefully we've got enough knowledge and preparation from various sources, that we'll be able to be successful against him."

Batting was New Zealand's downfall in most of New Zealand's recent matches against Sri Lanka, but the top order do not seem likely to fail again, with two key batsmen in form. Martin Guptill's sublime hundreds overshadowed Ross Taylor's efforts, but Taylor hit a fifty in each of the three matches against England, and has in the past been the most effective of New Zealand's batsmen against Sri Lanka's attack.

"Martin Guptill's batting has been world class the last week or so in this form of the game. We talked a lot recently about his batsmanship through some key stages in the game, and it's been outstanding. We're confident that Martin will continue that form, and also Ross Taylor as well. I think his performance has been very sound for us. Then some other guys have chipped in too."

While virtually all of Sri Lanka's first XI were still at the IPL three weeks ago, New Zealand have been in England for well over a month. McCullum suggested their lead-up into the tournament might also hand New Zealand a slight advantage in the match.

"We think we've got some match winners among our lineup, and we've had to become battle-hardened in English conditions over the last week or so. We are confident that it will give us some sort of assistance. We think we are a good one-day unit, with experienced players and a feel of the style of play which suits us."

Andrew Fidel Fernando is ESPNcricinfo's Sri Lanka correspondent. He tweets here