Gerard Lyttle says Linfield's record against their title rivals "should be a concern" for David Healy.
The Blues fell to a 2-0 defeat to Crusaders on Tuesday night, the second time they have lost to the Shore Road men in the Premiership this season.
In 11 league games against the current top six in 2022/23, Healy's side have won just two, drawn four and lost five.
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Wins against Glentoran and Larne have been the only successes for the champions so far, but they do remain firmly in the title hunt.
Despite sitting third in the table, and just four points off leaders Cliftonville, former Irish League manager Lyttle believes there is little room for error for Linfield - or any of the other title challengers.
He told Belfast Live's That's What I Call Football podcast : "It will be a concern for David, of course it will. At the end of the day if you want to go on a run and win the league, you have to beat the teams around you.
"And Linfield haven't been as consistent as David would have hoped. But every team in the top six has their own concerns.
"Crusaders can be inconsistent, Cliftonville's away form is patchy and they have recently struggled to keep a lead.
"Larne probably have the best defensive set-up and that gives them a good opportunity to put a run together, so it's interesting.
"But it will be a concern for David, no doubt about it. he will look to add one or two before the window closes. It isn't like them, because they usually have one or two signings by this stage of the window."
Linfield take on basement side Portadown this weekend before a massive triple header against Larne ( Irish Cup ), Cliftonville and Glentoran (both Premiership).
Former Cliftonville midfielder Barry Johnston believes big games are coming up for every side, not just the champions.
"You can say Linfield have these big games coming up, but you can also say Cliftonville have a massive test against Linfield," he added.
"There is so little between the top six teams that every fixture between the sides is a cup final. I was at Cliftonville vs Coleraine last Saturday and it had that feeling, nobody wanted to make a mistake.
"Every top six game has that potential. Linfield can go and win all three of these games, no problem. But they can also drop points.
"That's why this league is incredible right now and it is great to be part of."
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