WALES' Gloucester star Gareth Delve says the Guinness Premiership leaders are in for a tough time when they play the Ospreys in their huge Battle of Britain' clash on Saturday.

The massive Heineken Cup showdown at Swansea's Liberty Stadium will define the Ospreys' season.

Defeat is unthinkable for the Welsh region as they bid for a place in the quarter-finals of Europe's premier rugby competition - a feat they failed to achieve last season.

Finishing as one of the two best group runners-up is their only realistic hope of making the final eight with the West County club six points clear of the pool with just two games to go.

Delve missed Gloucester's 10-5 defeat in a quagmire at Bath last Friday with a niggling injury but is confident he will be fully fit to be in the mix when coach Dean Ryan selects his squad.

Delve, who won the first of his four Welsh caps as a replacement during Mike Ruddock's last game as national coach in the 2006 Six Nations 28-18 victory of Scotland at the Millennium Stadium, said: "I always enjoy coming back to Wales and playing in front of the Welsh fans but this game is special - a huge match against a great squad and just hope that I can play my part for Gloucester and that we come away with a result."

The 25-year-old former Bath player said: "However, the Liberty Stadium is a very hard place to go, as Cardiff Blues found out last week, and, if we turn up with anything less than our best game, it will not be good enough."

Gloucester deprived the Ospreys of a bonus point when they beat them in the corresponding match at Kingsholm 26-18 back in November.

But the Cherry and Whites' Cardiff-born back row forward said his side will have to be at their best if they have any chance of doing the double over their Welsh rivals: "Having strength in depth is what wins cups and enables teams to sustain the pressure during long competitions and we know that the Ospreys have world class performers all over the pitch and that we will have to give our best."

Great things are expected of the Ospreys this season after their star-studded squad was strengthened over the summer with former Rodney Parade favourite Ian Gough, dynamic Wales scrum half Mike Phillips, All Blacks star Marty Holah and the Tongan ex-Super 14 flanker Hale T-Pole.

The region are expecting the Liberty Stadium to be close to a sell-out after a crowd of 16,509 turned out for the New Year's Eve clash with the Cardiff Blues.

l The Ospreys v Gloucester game is live on Sky Sports this Saturday at 5.30pm