As the two sides prepare to face each other at Wembley on Saturday for a place in next year's Premier League, we take a look back at their play-off history in the last ten years.
Blackpool
The Tangerines returned to Division Two (now League One) in 2001 after a dramatic 4-2 play-off final win over Leyton Orient in Cardiff.
This was to be the beginning of the Blackpool revival, although they were still along way off where they wanted to be.
Blackpool would continue with their love of the play-offs in 2007 with a 2-0 win over Yeovil and would return to The Championship to mark their 100th overall season in the Football League.
In 2010 Blackpool would defeat Cardiff at Wembley to complete the play-off hat-trick and win promotion to the Premier League.
They have now been uniquely promoted through all three tiers of the Football League via the play-off system and face West Ham on Saturday hoping to make it four times in a row.
West Ham United
After being relegated from the Premier League in 2003, West Ham aimed to bounce back at the first time of asking when they travelled to Cardiff to play Crystal Palace a year later.
A semi-final victory over Ipswich made them the favourites, but a Neil Shipperley goal gave Palace a 1-0 win.
Despite the play-off heartbreak, The Hammers returned to The Millennium Stadium the following season with Preston North End the opponents.
Bobby Zamora scored the only goal of the game to elevate West Ham back to the Premier League.
Source: DSG
Source: DSG