Steve Staunton - wins his 99th cap.

By Ian Parkes, PA Sport, Oita

The Republic of Ireland begin their latest World Cup adventure against a Cameroon side fresh from their latest African Nations Cup triumph.

Under the guidance of German coach Winfried Schaefer, Cameroon appear to be stronger than in their last two appearances in the World Cup finals in 1994 and 1998, crashing out in the group stages on both occasions after failing to win a single game.

The Republic, meanwhile, are a squad still coming to terms with the very public fall-out between skipper Roy Keane and manager Mick McCarthy, the repercussions of which could still be evident when Ireland face Cameroon in Niigata on Saturday.

Here, we focus on the key battles which are likely to determine the outcome of the opening match in Group E.

STEVE STAUNTON v PATRICK MBOMA

Centre-back Staunton has the responsibility of skippering the Republic or Ireland following the ignominious departure of Keane last week, but his experience should prove invaluable to the Irish cause.

The record-breaking Staunton, who will make his 99th appearance for his country this weekend, faces a battle of the veterans with Mboma.

The 33-year-old wily campaigner will need to rely on his instincts to combat the physical nature of Mboma's game as the Cameroon striker has power in abundance.

Mboma, who spent the closing few months of the last Premiership season on loan with Sunderland, will undoubtedly put his knowledge of the English game to good use and so impose himself on the Republic rearguard.

MARK KINSELLA v LAUREN

Kinsella might consider himself fortunate to have benefited from Keane's absence, but it is an unenviable void he now fills.

It is said all eyes have usually been on Keane whenever the Republic have lined up with their opponents in the tunnel due to the fear he instils. No disrespect to Kinsella, but the same can hardly be said of the Charlton midfielder.

The 29-year-old does carry the mantle of the Republic's player of the year for 2000, so will not be fazed by the task he faces of holding the midfield line, although he comes up against a versatile figure in Arsenal star Lauren.

The 24-year-old was the player of the tournament in Cameroon's Nations Cup triumph and so is likely to make his mark again if given the opportunity, particularly with no Keane to keep him quiet.

ROBBIE KEANE v RIGOBERT SONG

There's only one Keano - and that is definitely the case now as Robbie is entrusted with the task of firing Ireland to glory.

Republic fans will be hoping to see a few of Keane's celebratory cartwheels over the next few matches as they did last weekend when the Leeds frontman warmed up for the tournament with a brace in a 2-1 win over Japanese club side Sanfrecce Hiroshima.

An impudent Keane on top form should prove a handful, even for experienced captain Song, who now plies his trade with Cologne after spells in the Premier League with Liverpool and West Ham.

Song's defensive capabilities are underlined by the fact he has been linked with a summer move to Bayern Munich.

However, he will be looking to avoid an unwanted and unprecedented hat-trick of being sent off in three successive World Cups following his dismissals in 1994 - when he became the youngest player at the age of 17 to receive a red card - and again in 1998.