Unbeaten Castleford Tigers face the acid test of their improvement with the visit of First Utility Super League champions Wigan Warriors, according to coach Daryl Powell.
The Tigers are one of the surprise packages of the season so far with three wins out of three but Powell knows the jury is still out on their play-off credentials.
"We've had a great start," said Powell, who succeeded Ian Millward midway through last season.
"It has given us a real good platform but we've some tough challenges to come and we're faced with one of those straight away on Sunday.
"It will give us a real sense of where we're at as a team."
Wigan are unbeaten in their last six visits to Castleford but the Yorkshiremen were 18-4 winners at the DW Stadium last June and Warriors coach Shaun Wane is preparing his side for their biggest test of the domestic season so far.
"They are a good team and it is a difficult place to go," Wane said. "We will need to be much better than we were last week against Wakefield.
"We have won at Castleford a few times in the past few years but I understand this is a challenge for us.
"Daryl is a smart coach, he has got himself a workmanlike team who all play hard for each other and they are throwing a lot at opposition teams.
"I will pick my best team for Sunday because this is our biggest test so far."
Wane recalls full-back Matty Bowen, England winger Josh Charnley, centre Dan Sarginson and forward Eddy Pettybourne and includes veteran prop Jordan James for the first time since he rejoined the club but skipper Sean O'Loughlin misses out with a shoulder injury.
Warrington Wolves half-back Gareth O'Brien is confident his side will make it back-to-back wins when they take on London Broncos at The Hive.
The Grand Final runners-up lost their first two games to St Helens and Leeds Rhinos but got off the mark against Hull FC last Sunday and O'Brien expects them to kick on.
"As a team we've seen a steady improvement," he said. "We are still probably not where we want to be defensively, we still want to tweak a few areas.
"If we sort our defensive attitude out, the attack will take care of itself. Hopefully we can do that this weekend."
Warrington are set to give a debut to full-back Matthew Russell after he completed his rehabilitation from an ankle injury sustained in pre-season training while forward Glenn Riley has also recovered from a knee injury to take the place of Anthony England.
Former Melbourne outside back Denny Solomona, who is due to fly into London on Saturday morning, has been included in the Broncos' provisional squad, along with Iliess Macani who will be vying with him to replace injured full-back Nesiasi Maitatonga.
Something will have to give at the Rapid Solicitors Stadium, where Wakefield Trinity Wildcats and Catalan Dragons will both seek their first points of the season.
The Wildcats will give debuts to former Bradford Bulls prop Nick Scruton and winger Chris Riley, who has joined them on loan from Warrington, but hopes of including Australian half-back recruit Harry Siejka were dashed when his arrival was delayed.
The Catalans, who are without 11 senior players through injury and suspension, are set to give forwards Louis Anderson and Benjamin Garcia their first appearances of the season while reserve team prop Gadwin Springer could make his Super League debut after being named in coach Laurent Frayssinous' 19-man squad.