Top-of-the-table host third-placed Liverpool at Emirates Stadium on Saturday evening and Redknapp believes the game will say a lot about the two sides' chances of maintaining those positions until the end of the season.
He told Sky Sports: "Arsenal are top of the Premier League but, despite some impressive performances, many people would have expected them to get the results they have done so far this season.
"The only team they've faced in the league from last season's top five has been Tottenham, who they beat 1-0, while they've lost in the Champions League to Borussia Dortmund and in the Capital One Cup to Chelsea in the past 10 days.
"Liverpool, meanwhile, defeated Manchester United 1-0 in their only game against a top five side from last season's campaign.
"That's why this game holds so much fascination - it will tell us a lot about each side's chances this season."
Redknapp believes the outcome of the game may depend heavily on how Arsenal's centre-back pairing of Laurent Koscielny and Per Mertesacker cope with Luis Suarez and Daniel Sturridge.
"Arsene Wenger's side have enjoyed a great run of form since their win over Bayern Munich in the Champions League last season and I've enjoyed watching them this year with new recruit Mesut Ozil, Aaron Ramsey and Olivier Giroud in great form," Redknapp said.
"The pairing of Laurent Koscielny and Per Mertesacker at the back has also been key - but those two players face a really tough test this Saturday.
"Liverpool have been blessed with some great striking partnerships over the years, and Daniel Sturridge and Luis Suarez, although not a typical blend up front, have been combining brilliantly.
"If you described them you'd say they were selfish players but their partnership is instinctive and it works. They look for each other if they can't score themselves and so far they've bagged 16 goals between them.
"The system Brendan Rodgers is employing also helps. With three at the back Liverpool are able to get three in midfield and their best two forwards on the pitch. That's one of the reasons why Liverpool are performing so well this season - and why Sturridge and Suarez are producing the goals and assists to win games.
"Prior to Arsenal's win at Anfield last September, I expected Mertesacker, because of his size and Suarez's low centre of gravity and style of play, to struggle against the Uruguayan. But he dealt with him really well.
"The problem Mertesacker has this year is that Sturridge will be playing, too. He's certainly going to have his hands full at the Emirates."
Redknapp also believes Arsenal face a battle in midfield in the absence of Mathieu Flamini.
He said: "Although Mikel Arteta will play, they will have to be extremely careful when they lose the ball.
"Arsenal struggled to cope with Chelsea's quick transition from defence to attack in the League Cup on Wednesday, and, with Sturridge and Suarez up front, they will have to be extra cautious of being hit on the break by those two.
"These are the challenges Arsenal need to face and overcome, though, if they want to be considered genuine title contenders this season.
"There will be a few nerves around the Emirates if things don't go their way, following the disappointing results against Borussia Dortmund and Chelsea, but the players need to find plenty of character and come up with a big performance.
"With the different formations, strong attacks and talent on the pitch it should be a fantastic game - albeit one that's hard to predict.
Liverpool are fortunate Theo Walcott and Lukas Podolski aren't fit because with their pace out wide they could have exposed their system - which players such as Ramsey or Jack Wilshere aren't likely to do when they come inside off the flanks - and I think they'll capitalise on that.
"I'm going for a 2-1 win for Liverpool."