The hosts were the better side for large spells of the contest but it was Cambiasso’s unfortunate touch off Wes Morgan’s header in the 47th minute that ensured West Brom took home the bragging rights.
The Baggies have now lost only once in six league matches while Leicester have picked up just one point from five fixtures that included Swansea, Newcastle, Burnley and Crystal Palace.
A disappointing performance last weekend prompted Nigel Pearson to make four changes to the Leicester line-up as leading scorer Leonardo Ulloa, without a goal or a shot in his last four matches, was dropped to the bench.
Marcin Wasilewski was among those to come in and he tested Ben Foster with an early header from Matty James’ corner before the West Brom keeper almost got himself into trouble when he carried the ball suspiciously close to the edge of the penalty area.
Saido Berahino looked dangerous with his pacey runs in behind Leicester’s defence and with quarter of an hour gone, the in-form striker finally beat the hosts’ offside trap but his shot was held by Kasper Schmeichel.
At the other end, referee Stuart Attwell turned down two penalty appeals in quick succession as Craig Dawson met a Leicester free-kick with the top of his arm before Joleon Lescott cleared out both man and ball after Jamie Vardy had latched onto Craig Gardner’s sloppy back-pass.
It was from set-pieces that the home side looked most likely to break the deadlock.
Morgan flashed a header wide from another James corner and moments later City’s captain was involved again as the ball dropped to Danny Drinkwater eight yards out but the midfielder’s shot was blocked.
Leicester’s encouraging first-half display was almost undone shortly before the break by a quick West Brom counter-attack as Stephane Sessegnon slid through Berahino, who teed up Chris Brunt on his favoured left foot but the winger fired over.
Pearson had cause for optimism at the interval but two minutes after the restart, his side fell behind.
Berahino was involved again, skipping in behind and as he cut the ball back, Morgan’s attempted header away deflected back off Cambiasso and into the Leicester net.
The home side cranked up the pressure as the hour-mark approached and Vardy could have equalised when Paul Konchesky’s long ball forward caught West Brom napping but after cutting back onto his right foot, the striker drove straight at Foster.
The Baggies had a strong case for a penalty when Sessegnon’s chipped pass struck Wasilewski’s hand but Leicester survived and Pearson threw on Ulloa for David Nugent with just over 20 minutes to play.
The Argentine almost made a telling contribution straight away as his cross from the right found Andy King in the area but the unmarked midfielder could only find Foster with his header.
Leicester continued to huff and puff in the dying minutes, bombarding West Brom’s box with crosses and long throws but the visitors’ defence held firm until the final whistle which was greeted with a chorus of boss from the home supporters.
Matt Le Tissier’s verdict
Nigel Pearson will be very disappointed. Going forward, in the early weeks of the season Leicester looked threatening. Even in games where they didn’t take all three points they still looked like they were going to threaten the goal. At the moment they are not creating enough clear-cut chances to try and win Premier League football matches. The best they could come up with today was a header from Andy King straight at Foster. I saw their first three games and turned round and said they won’t go down because they have too much quality – and they did have at that point. Unfortunately when they have come up against the teams that will be around them in the league they haven’t come up with the goods.
He will be massively disappointed, but on the other hand did they really deserve to lose this football match? Probably not. West Brom didn’t create very much either. It was a freak own goal. West Brom were equally as poor as Leicester and looking at it as a whole, I think a draw will be a fair result. I think West Brom will be absolutely delighted.