Wales assistant coach Rob Howley is wary of in-form England half-backs Danny Care and Owen Farrell ahead of the neighbours' make-or-break clash next weekend.
Scrum-half Care and England number 10 Farrell have proved influential performers behind England's push to land the RBS 6 Nations title this season.
Wales are next up at Twickenham in eight days' time - a game that is set to keep one country's championship hopes alive and end the other's.
And former Wales and British and Irish Lions scrum-half Howley has been impressed by what he has seen from two of England's key tactical controllers.
"I think they are two fantastic players," he said.
"Their ability to make individual decisions, they've got a great combination between them and they complement each other.
"Danny Care is a key player. He is instrumental when he plays for Harlequins in terms of the speed and tempo he brings to the game.
"His ability to implement a good kicking game is really important to England and his ability to speed up the game. He brings other players into the game.
"Care brings a zest and an energy and a tempo to the England game. He certainly brings the forwards into the game and asks questions around that guard and defensive line.
"We just have to be on our wits because defensively we were really good against France. But Care, as well as Owen's running game, can certainly ask a lot more questions.
"Having worked with Owen Farrell, his kick-pass-run decision-making is very good. He has obviously got a great kicking game."
Wales centre Jonathan Davies, meanwhile, looks to be closing in on a possible return next week.
Davies has seen just 40 minutes of competitive action since suffering a torn pectoral muscle during Wales' Millennium Stadium loss to South Africa four months ago.
But he will feature for the Scarlets in their RaboDirect PRO12 appointment with Munster today, when Wales' coaching staff will closely monitor his progress.
Davies, Scott Williams, Cory Allen, Owen Williams and Ashley Beck were midfield options all unavailable to Wales boss Warren Gatland for the title-reviving victory over France a week ago, and wing George North was moved to outside centre alongside Jamie Roberts.
A fully-fit Davies firing on all cylinders, though, would undoubtedly enhance Welsh prospects of stalling England's title bid and keep the reigning champions on course for a record third successive Six Nations crown.
Lock Alun-Wyn Jones, meanwhile, has not yet resumed training after missing the France game due to a foot infection. His absence meant a first Test start for the Scarlets' Jake Ball.
"We hope he will be able to train on Saturday morning and next week, so we will see how he is," Howley added.
"We were disappointed to lose him just before the France game, but he had been on antibiotics throughout the week. His well-being is fine, so we will just wait and see."