After falling behind to Tomasz Radzinski's opener, the ten-man Hammers saw the subsequently dismissed Bobby Zamora level and, with two-goal Yossi Benayoun twice giving them the lead, it looked as though they were on their way to their first Premiership victory of 2007.
But Fulham had other ideas and having seen Brian McBride level once, Christanval struck in the 92nd minute to rescue a dramatic last-gasp point.
Christanval was soon in the thick of things hauling down the escaping Carlos Tevez at the expense of the first of Graham Poll's ten yellow cards as the pair raced in hot pursuit of Benayoun's through ball.
But it was to prove even more costly for West Ham as Tevez was consequently forced to retire with a calf injury alongside James Collins, who had limped off seconds earlier with a recurrence of his season-long groin problems.
With substitutes Jonathan Spector and Zamora already on the pitch inside 13 luckless minutes, the afternoon got even worse for Hammers boss Alan Curbishley when George McCartney conceded a needless corner on the quarter-hour mark.
And when Wayne Routledge sent over the flag-kick, Heidar Helguson lost his markers to head the ball into the path of Radzinski, who gleefully prodded past Benayoun on the line to send Upton Park into an eerie silence of despair.
Desperate times call for desperate measures though and on 28 minutes Zamora rounded off a simple yet effective direct play to lift the East End gloom when he beat Christanval to Carlton Cole's flick-on and rifled an angled shot through Jan Lastuvka's legs.
After an ugly end to the first half which resulted in yellow cards aplenty, Benayoun took just 13 seconds to conjure up a moment of second half beauty.
Zamora chested the ball into the path of the innovative Israeli, who floated an inch-perfect 18-yarder over the stranded Lastuvka and under the crossbar.
Down but not out, Fulham levelled on the hour when Moritz Volz returned a half-cleared corner back into the area where McBride rose highest to head the ball past Roy Carroll from eight yards.
The Cottagers' joy was short-lived, though, for within five minutes West Ham had regained the initiative thanks to the tenacity of Benayoun.
This time a combination of industry and invention saw the Israeli playmaker hustle and bustle his way between Carlos Bocanegra and Christanval on the edge of the box and, after riding Lastuvka's desperate lunge, he coolly restored the lead with a low shot into the net.
Despite the outbreak of football, Poll was still keeping himself busy booking Helguson for dissent and Zamora for upending Radzinski.
And when the Hammers striker senselessly scythed through Franck Queudrue with 15 minutes remaining, Zamora saw red leaving ten-man Hammers with their backs firmly to the wall.
Wobbling West Ham finally collapsed two minutes into stoppage time. Substitute Vincenzo Montella sent another ball into the heart of the fragile defence and when Liam Rosenior's header was nodded on Christanval was not to be denied.