The viral, created by Wunderman and RKCR/Y&R, shows an irritating and talentless footballer mis-kicking the ball in the direction of Phillips, who is leading a horse out of its trailer.
He sprays an excessive amount of aftershave over himself and then walks over to Phillips, unaware of who she is, and attempts to flirt with her.
The footballer reveals his ignorance by stating that there is no skill in horse riding and that it's not a real sport like football, at which point the horse sneezes violently coating him in snot.
The spot follows a previous viral, starring the same footballer and the English Rugby Union player Josh Lewsey, supporting the England rugby team. Land Rover said that it was viewed by more than 1m people last year at the start of the Rugby World Cup.
Land Rover aims to reach a broad audience with the viral and endorse the fact that eventing, with its three disciplines of show jumping, dressage and cross country, is a tough sport for truly skilled athletes.
Land Rover is the official vehicle of the British Eventing team and Zara Phillips, a European and world gold medallist, has been its ambassador since 2006, appearing in two previous ads. This included "beautifully poised", (pictured), which was shot by Mary McCartney and broke in December 2006.
The viral launches today, on websites including YouTube and Google Video, in the run-up to the Olympics in August and before an autumn of equestrian events, including the Land Rover Burghley Horse Trials.
Andy Griffiths, marketing director for Land Rover, said that the car manufacturer does not use viral that often in its campaigns and that it wanted to target "younger, more tech-savvy people".
He said: "With the summer games coming up it's a great opportunity to get added cut-through in the coming months. I have high hopes for the campaign."
Sav Evangelou, group creative director at Wunderman, said: "Through this viral we're creating a reason for people who have no relationship with Land Rover or with eventing to engage with us. By throwing it into the public arena we aim to drive debate, whilst providing entertainment."