Dean Ryan is yet to decide whether to hand the Gloucester No 10 shirt to Ryan Lamb or Olly Barkley for Saturday's EDF Energy Cup semi-final against Ospreys.

Carlos Spencer, who signed from Northampton last month, has started Gloucester's last six matches – but is cup-tied this weekend.

Ryan must therefore make a change in the pivotal position for the clash at the Ricoh Arena in Coventry – and is torn between Lamb and Barkley.

Lamb is an out-and-out fly-half but has fallen out of favour since the arrival of Spencer, while inside centre Barkley has started just two games in the No 10 shirt all season.

When asked whether Saturday's match presented a big opportunity for Lamb, Ryan said: "It's an opportunity for whoever plays 10.

"Carlos is cup-tied, but that is something we have always known, so it has not come as a surprise. We always knew we would be without Carlos at this stage.

"We will make a decision on who replaces him when we have looked more at the Ospreys and more at how people have been this week."

On Barkley, Ryan said: "We have only got two options to play 10 this weekend and he will be one of them."

Lamb's position within the squad is intriguing, with rumours circulating that he will be allowed to leave Kingsholm this summer despite having a further year to run on his contract with the club.

The 22-year-old, who was born and bred in Gloucester, has attracted the wrong kind of headlines recently after being fined £1,000 by magistrates in Cheltenham after admitting punching a man in the face outside a nightclub.

Asked whether he expected Lamb to prove his worth the next time he is handed a starting role for Gloucester, Ryan was cautious.

He said: "We will only know that when he goes out at the highest level again – and we will see that if he gets a chance this weekend."

Ospreys will be without Wales full-back Lee Byrne for Saturday's match after he limped out of the Six Nations finale against Ireland with a foot injury. He could be replaced by Gavin Henson, Jonny Vaughton or Gareth Owen.

Ospreys' Wales hooker Richie Hibbard has an ankle ligament injury, while lock Ian Evans, prop Duncan Jones and winger Nikki Walker are also ruled out.