Billy Vunipola rejoined Eddie Jones' title-chasing squad with a ringing endorsement from former England number eight Dean Richards.
Richards, who won 48 caps for England, most of them from Vunipola's position at the back of the scrum, witnessed close up the Saracens forward's destructive powers as he helped steer the Aviva Premiership champions to a 35-27 victory over Richards' Newcastle at Kingston Park.
It was Vunipola's first game since he was carried off on a stretcher during England's win over Argentina in November and came three weeks ahead of schedule, but it looks to have clinched his return to the national team.
"It's somebody else's call but he's clearly a good player," Richards said. "I was looking at my team more than theirs but he certainly had an impact on the game.
"He's incredibly strong and on his day I think he's the best in the world - I don't think there's anybody in world rugby that can touch him - but he's got to be fit."
Vunipola pronounced himself fit after playing 72 minutes of Sunday's game and looks certain to win his 33rd cap in the Calcutta Cup match against Scotland at Twickenham on Saturday.
"He's incredibly strong and on his day I think he's the best in the world"
Jones' men will be aiming for a record-equalling 18th successive victory to remain on course for a successful defence of their RBS 6 Nations crown.
He was one of 30 players to assemble at Pennyhill Park on Sunday and was joined by older brother Mako, who also gained precious match fitness against the Falcons, and another Saracens team-mate, fly-half Alex Lozowski, who scored 20 points in Sunday's game with two tries and four goals.
Also included in Jones's squad is Bath winger Anthony Watson, who has recovered from a hamstring strain.
Jones will name his 23-man squad to face Scotland on Thursday.
Ireland host England on 18 March.