Wales' record try scorer Shane Williams says it is "a little bit premature" to talk about winning the World Cup.
Coach Warren Gatland believes Wales can win the World Cup in 2015 after securing only their second ever win over South Africa.
But Williams says the tournament is a long way off even though the team are in a better position than they were at the start of the autumn series.
"It's great to be confident but there's a long time in between," Williams said.
Wales beat South Africa 12-6 at the Millennium Stadium, ending a run of 22 consecutive defeats against the southern hemisphere "big three".
Gatland says the win is an important landmark and he believes his side can win the World Cup in 2015 "if we get the bounce of the ball."
Williams, a member of the Wales side that reached the World Cup semi-finals in 2011, says the focus for now must be the Six Nations campaign which begins against England on 6 February.
"I think it's a little bit early and premature to start talking World Cup and winning it," Williams added.
"If I was coach I wouldn't even be speaking about the World Cup at the moment because it's a very tough Six Nations you've got to get through and hopefully win.
"However I think they are in a better position now than they were two, three weeks ago.
"They've got to talk and be confident because they're a very good squad and they've proven they can beat the best in the world when they perform on the day."
Gatland's record as Wales coach against the southern hemisphere sides had come under scrutiny in the build-up to the South Africa game.
|Wales' 2015 World Cup Pool A matches|
|Sunday, 20 September: Wales v Uruguay (Cardiff)|
|Saturday, 26 September: England v Wales (Twickenham)|
|Thursday, 1 October: Wales v Fiji (Cardiff)|
|Saturday, 10 October: Australia v Wales (Twickenham)|
Wales had lost 26 of their 27 games against the All Blacks, Australia and South Africa since Gatland took charge in 2007.
But former Ospreys wing Williams, who in November confirmed his retirement from rugby to focus on a coaching career, says the win lifted the pressure.
"It was a game they had to win," Williams told BBC Radio Wales.
"The pressure was on, certainly the coaching staff, and the players themselves but they went out there and proved a very big point.
"The win was exactly what the coaches and the players needed especially going into a big Six Nations.
"Hopefully it builds the momentum going into the Six Nations."