Rhys Webb injury: Rivals for scrum-half spot 'must deliver' warns Mike Phillips
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Whoever plays scrum-half in the Six Nations "has to deliver", says former Wales international Mike Phillips.
Wales' first-choice scrum-half Rhys Webb will miss this year's Six Nations with a knee injury, which Phillips has described as "a massive blow".
Scarlets scrum-halves Gareth Davies and Aled Davies, and Blues' Tomos Williams, are the half-back contenders.
Phillips said: "It's a vital position and these guys have to deliver on the big occasion."
Phillips, who came out of retirement in December 2017 to play twice for Scarlets in the Pro14, is Wales' most capped scrum-half with 94 appearances.
Gareth Davies already has 27 Wales caps compared with Aled Davies' five, but the latter started in Wales' most recent fixture - a 24-22 win over South Africa.
Phillips believes both can still have a big impact on this year's Six Nations.
"Webb and Gareth Davies have been battling it out for the number nine jersey for years," said Phillips.
"Davies has got an opportunity now and so does Aled [Davies].
"Aled has a great pass and he's crisp, and Gareth is very sharp off the mark so it's a good blend."
Wales' other option at scrum-half is uncapped 23-year-old Tomos Williams, who has been called up to the squad in Webb's absence.
Williams has played more games for Blues this season - 19 - than any other player, scoring tries in each of his last two appearances.