Ian Evans holds the key for patched-up champions Wales

Aerial power of 6ft 8in lock is vital for Wales to prove doubters wrong against buoyant Irish

According to Rob Howley, the locks will hold the key to Wales setting out on the defence of the Six Nations trophy with a win against Ireland at the Millennium Stadium today. Well, the locks and the Glamorgan-bowler-turned-Scarlets-flanker who will be seeking to bring a googly factor to the lineout mix as the 2012 Grand Slammers bid to stop the rot of a seven-game losing streak.

"In international rugby it is important that you have a solid platform and a quality of possession and lineout in the best place to attack from," said Howley, Wales' interim head coach in the absence on Lions preparation duty of Warren Gatland. "The lineout game against Ireland is always key. When we've played against them recently there has always been a number of lineouts in the game and we need to have options in that area."

Howley's second-row options for facing an Ireland squad who will arrive in Cardiff in buoyant mood – on the back of their 47-point pummelling of Argentina at the end of the autumn and with Brian O'Driscoll, Rob Kearney and Sean O'Brien all back in harness – have not exactly been plentiful. Alun Wyn Jones, Luke Charteris and Bradley Davies are all on the injured list, together with Ryan Jones, the flanker-cum-lock. Hence the fast-tracking of the former computer software salesman Andrew Coombs for debut-day duty – and the retention at blindside flanker of Aaron Shingler, a former right-arm medium pace bowler with Glamorgan's second string who has made a significant contribution in the lineout in his four international appearances to date.

Hence, too, the selection for bench duty of Olly Kohn, co-owner of the Jolly Hog hog-roast and sausage company. The uncapped Harlequins lock was born in Bristol and raised in the English west country but qualifies for the Principality because of a grandfather who hails from the Rhymney Valley.

The key to Wales' success in the key area, however, is likely to be in the hands of Ian Evans. The giant Osprey has not played since suffering a knee injury against Samoa 11 weeks ago but his aerial influence is likely to prove as vital to the Cymru cause as that of the all-Lions front row of Gethin Jenkins, Matthew Rees and Adam Jones and the orchestrating of Dan Biggar from outside-half.

Biggar will be making his first appearance in a Six Nations match. Evans will be making his 10th. He has yet to experience defeat in the championship. It might not be insignificant that the 6ft 8in, 18-stone totem was involved in every Welsh match-day squad in last season's Grand Slam campaign – and in the 2008 one.

Born in Johannesburg but raised in Aberdare, Evans will bring attitude as well as experience with him. Like the rest of Howley's squad, the 28-year-old is out to prove a point after the anguish of the close-call summer defeats in Australia and the autumn whitewash that followed.

"One thing I notice about Wales players is as soon as people start putting pressure on us and doubting us, we stand up and we want to be counted and to prove people wrong," he said. "A lot of people have got opinions, and they are entitled to those. You have just got to accept that, really, and you have got to prove them wrong.

"Every time you come into a Six Nations campaign it is a fresh start. You have got to get that first win. I think we proved a lot of people wrong in last year's Six Nations. It's important to start well. That gets the ball rolling."

There is no doubting the pivotal nature of the lunchtime kick-off in Cardiff. Next up for Wales is France away. If they lose today and are down and out in Paris, they will travel to Rome for game three just 80 minutes short of equalling their all-time record losing streak of 10 matches.

As for the Irish, they have England next, in Dublin a week tomorrow. Declan Kidney's men arrested their own slump in form with their seven-try demolition of an Argentina team that had just won in Cardiff. They have lost their last three matches against Wales but have O'Driscoll back at outside centre for what looks like being his Six Nations swansong season and Kearney back at full-back for a Lions audition against Leigh Halfpenny.

The 2009 Grand Slammers also have O'Brien at openside flanker. The wrecking ball of a Dubliner missed the autumn because of hip surgery but is back for another intriguing head-to-head – against Wales captain Sam Warburton, who has overcome the challenge of the in-form Justin Tipuric to keep the red No 7 jersey.

"Wales has become a championship-defining match," O'Brien said. "You can't win a Grand Slam on the first day, but you can lose one if you don't make a good start.

"There's a bit of hurt on our part after losing the last three against Wales and we want to put that right. Things didn't go our way last year, which was unfortunate because we played so well at times during the game. But we didn't play for the full 80 minutes, which is what we're looking to do this time.

"Wales may have lost seven in a row, but I don't think they'll be nervous at all. It's obviously a massive game for us. Wales are very tough opposition. The set-piece and breakdown will be massive."