The Welshman netted the opener against the Hammers before an Andy Carroll penalty and a goal from Joe Cole put the hosts ahead. However, Andre Villas-Boas' side rallied, and it was Bale who had the final say in the 90th minute with a spectacular left-footed effort to clinch the points after Gylfi Sigurdsson had levelled.
Spurs now face the Gunners at White Hart Lane on Sunday, and Parker believes the manner of their win at Upton Park will be a blow to the confidence of their bitter rivals going into the game.
Parker told Sporting Life: "I've been in that position where you're watching the scores come up (on television) and it goes 'last minute goal at wherever' and you're praying it's the other team - and it isn't, it's the team that you don't want to score.
|AVB HAILS 'SPECIAL' BALE
|18/1||Tottenham are 18/1 with Paddy Power to beat Arsenal 3-2 on Sunday
"So it is deflating as a player on the opposite end, and I'm sure the Arsenal players are like that.
"I'm sure they'll be thinking they need to concentrate on themselves and try to win the game against us, and if they win the game against us it goes down to a point so it's going to be tight."
The Lilywhites know victory over Arsenal will take them seven points clear of Arsene Wenger's side, who pipped them to Champions League qualification last term, an outcome which Parker is keen to avoid in this campaign.
"What happened last year drives us," added the veteran midfielder. "It's a focus and it's something we're aware of. We've worked really hard this season to get where we've got, and we can't afford to fall off it.
"The race for fourth place isn't over but we fully deserved the win against West Ham. Their goalkeeper had a world-class game, but we still managed to get the three points."