His talent was rumoured widely and in 2002, at the age of only 15, he signed a contract with Spanish Valencia CF.

He played 9 matches for the Valencia CF reserves with names like David Silva, Raul Albiol, Mohamed Sissoko and Jaime Gavilan.

However, things didn't work out as expected when the reserves Valencia CF Mestalla suffered relegation to the Tercera División where young foreign talents were not allowed to play according to Spanish FA regulations.

[2] On 12 September 2004 (aged 17) he got his Danish Superliga debut for his childhood team AGF Aarhus in a home game against Viborg FF.

After 1+1⁄2 years in Spain, playing Segunda División B for CD Eldense and Orihuela CF, he finally returned to Denmark on December 20, 2007, and signed a 1⁄2-year contract with Vejle BK,[3] which in 2008 was extended for another six months.

In the summer 2010 Hobro IK announced, they had received a bid from Arietta's former team AGF Aarhus.

The playing time was not helped on the way after a bad injury in March 2014, where he damaged his knee and was out for the rest of the season.