Ulster are one of best the sides, admits John
Cardiff Blues believe they are taking on one of the best teams in Europe when they welcome Ulster tonight.
Both teams have endured a mixed start to the new Guinness Pro12 season after each claimed one win – both against Zebre – from their opening two games.
And that will only serve to raise the stakes at the Arms Park.
Blues assistant coach Paul John said: "Ulster are a cracking team, one of the best in Europe, let alone the Pro12. They are a good all-round side. They have a strong pack, big ball carriers and players who can attack from all over the park.
"They have really good half-backs in Paul Marshall, Paddy Jackson and Ian Humphreys and real quality on the wings in the likes of Andrew Trimble and Tommy Bowe. So our defence will really need to be on the mark to stop their runners.
"They have been up their competing for the title in recent years as well as doing well in Europe so we know the size of the challenge.
"We rose to that challenge at the Arms Park last season with a huge effort and it will take a similar performance to do it again."
Blues lost their opening home game of the season to Glasgow Warriors despite a vastly improved display from their forwards that left coach John frustrated.
He said: "We played really well for an hour but fell short in the final 20 minutes. The scrum was strong and our lineout won ball but it's about how you use it.
"Our ball retention just wasn't good enough because turnovers resulted in Glasgow scoring two easy tries that took the game away from us.
"That was hugely disappointing and something we have been working on this week."
Cardiff have also opened the door for a shock return to Wales for British & Irish Lions full-back Leigh Halfpenny.
The 52-cap star could see his £450,000-a-year contract terminated by the European champions having yet to play for his new club following his summer move from Cardiff due to shoulder and groin injuries.
Now he could be the first to benefit from the £3.2m set aside by the Welsh Rugby Union and regions for dual contracts.
Chief executive Richard Holland said: "If the reports [about Halfpenny's contract] are true then we are extremely keen to have him back.
"We offered Leigh a contract to stay and would be interested if we he was available, if that was on a regional deal or dual contract."
John added: "He played for a few years for us so I know the players would love to see him back."
Toulon are investigating whether Halfpenny was injured when he signed earlier this year having undergone surgery in March after he dislocated his shoulder in Wales' 28-19 defeat at Twickenham.
The French club's president Mourad Boudjellal said: "We haven't excluded denouncing his contract.
"We are awaiting the medical update. The problem that we have now is that we think he may have arrived at Toulon with that injury. We are conducting an investigation."