The Gunners were beaten 2-0 by West Ham in their opening game and Nicholas is worried by their defending.
The Gunners have been touted as potential Premier League champions this season after an impressive ending to the last campaign saw them retain the FA Cup and become one of Europe’s in form teams.
However, they were beaten 2-0 by West Ham in their opening game thanks to a poor defensive display, with Petr Cech putting in an uncharacteristically poor performance. And Nicholas says they must improve that defensive frailty if they are to challenge this season.
“You can have all the good ingredients going forward but if you don't sort your defence out you won't win anything,” he told Sky Sports.
“It's not a pleasant feeling on the first game of the season when your major signing of the summer is a goalkeeper, who has got us all excited, and he's involved in mishaps with his defence straight away. It was an eye opener, a wake-up call.”
Defence a weak point
While manager Arsene Wenger has been busy improving his attacking options in the transfer market in recent seasons with purchases such as Mesut Ozil and Alexis Sanchez, the defence has largely remained the same.
That said, Nicholas believes Gabriel Paulista will challenge regular centre-half Per Mertesacker this season while young defender Calum Chambers is also being touted for a future in that position.
For now though, Nicholas remains concerned that their defence will be considered weaker while the emphasis is on attacking football.
“(Per) Mertesacker did look better in pre-season but I think he'll come under pressure from Gabriel Paulista,” he added.
“Calum Chambers is being groomed as an out and out centre-half, so they do have cover in that department [but] I genuinely feel that Arsenal will always be associated with having weaker defenders because so much effort is about attacking play.”