Ospreys head coach Lyn Jones is determined his side will learn from recent defeats and book their place in the EDF Energy Cup semi-finals.

The Magners League champions were toppled by Gloucester and Leinster in their last two outings and Jones blames the same shortcomings for both results.

A solitary match point or preventing Harlequins getting a five-point haul at Twickenham Stoop on Sunday would see Ospreys progress to the last four of the Anglo-Welsh Cup.

Jones said: "We face a Harlequins side who are on top of their game - they narrowly lost to Gloucester last weekend but played very well.

"They are no different to a number of English sides in that they have a strong set piece and an appetite to play for territory.

"Having been edged out in our last two fixtures for similar reasons, our players are determined to put things right against Quins.

"We travel in a buoyant frame of mind boosted by the return of our Welsh internationals."

Gavin Henson and James Hook are among the Wales stars back in the starting line-up following last Saturday's 34-12 defeat by the world champions Springboks.

Quins have not given up hope of halting the Ospreys' seemingly unstoppable march into the last four, naming a strong side for the only meaningful fixture in Sunday's schedule.

In two changes to the side edged 27-25 at Gloucester, Adrian Jarvis replaces the injured Chris Malone at fly-half and Will Skinner comes in for Paul Volley at openside.

England winger David Strettle continues his midfield partnership with former Springbok De Wet Barry, with Simon Keogh and Ugo Monye on the wings.

Bristol are without Mark Regan for the dead rubber against Leeds following the England hooker's appearance for the Barbarians against Bristol on Friday.

Head coach Richard Hill is ready to give young prospects such as Dave Attwood, Redford Pennycook and James Phillips a chance against Leeds and is expecting some hungry displays.

Hill said: "It will be a big occasion for some of our younger players starting at home in a competitive game.

"These lads are really fired up. There are a number of young players there looking for a long career at Bristol."

London Irish and Worcester are sharing Hill's approach for their clash at the Madejski Stadium - another game with nothing at stake.

Argentina centre Gonzalo Tiesi makes his first start of the season for the Exiles.

More news from SportingLife.com