The 27-year-old began his career just over a decade ago and he was considered a wonderkid for his performances at his hometown club Hércules.
He first went to Barcelona and then Real Madrid, after a fallout in the La Masia academy. He trained with Lionel Messi and Cristiano Ronaldo, but he admits that he was most impressed by Xavi Hernandez's abilities with the ball, as he opened up about why he failed to make the grade at the giants of Spanish football.
"Yes, I trained with Lionel Messi and Cristiano Ronaldo and it was always great but the guy that surprised me the most was Xavi Hernandez because in the midfield, he never lost the ball," Femenia told Goal . "When I used to train with him, he was incredible.
"I was only 17-years-old and I was doing what I enjoyed [at Hercules]. Now I have gone from good to bad moments, from bad back to good. I learned from my mistakes in the past while I was young but now I am doing what I enjoy so I only think about this.
"Going to Barcelona is always right the right decision, just like going to Real Madrid and Castilla. It is true that I didn’t have the best experience of my professional career there [in Barcelona] but I think everything helps you to grow professionally and as a person.
"I think the main thing was that when I was in Hercules. I was the wonderkid and the guy that everyone was looking at. When I went to these big teams, I was just one more player and I think this was the big difference between what I was expecting, as a youngster, to be the wonderkid again.
"I was not one, I was just one of the group. That's the bit that hurt me most, I didn't feel as important as I was in my previous club I think this was the big thing that changed my career."
Femenia was valued highly by Barcelona, who paid £3 million to secure his signature. He was ultimately released, however, and signed for Real Madrid just hours later.
But he couldn't make the break through to the first team in Madrid either and he dropped into the second division in Spain for Alcorcón. He then moved to Deportivo Alaves who were one of Spain's true success stories.
He won the league and competed in the Copa Del Rey final with Barcelona at the Basque club, becoming one of their key players, and Femenia admits he had to be humble to start fresh after getting lost in his big club experiences.
"No, it was not a big problem to go down because sometimes in life you have to make one step backwards to take two steps forwards," He added. "I think that these are the things that you have to do and it was not a big problem for me.
"It was difficult to leave Alaves in the end as I enjoyed being there, but professionally I wanted to grow and in the end it was the right decision. I had other offers in Spain, yes. In the Premier League, I had Watford.
"I also had the opportunity to make my dream come true and play in the Premier League, it was something that I always wanted to do."
Femenia cites his two first managers at his boyhood club as the biggest influences on his career, in Esteban Vigo and Miroslav Dukic.
The Alicante-born defender still cites achieving promotion to La Liga as a teenager, with his boyhood club, as one of his best footballing memories.
"Well, I have to say a great memory was when we won and went up with Hercules," he continued at Watford's London Colney training ground. "That was one of my best memories as I was starting to play regularly in the first team. It is a big memory for me.
"I was born there, it is a city I love. The city I grew up in. I love to go back, when I have the time, to see everyone. I began in Hercules in Alicante. That was the team of my city, of course, when you are a kid you never think you are going to make it. To play in the top two leagues in the world. I managed to do it and that’s good."
Femenia's career has seen him play alongside a number of big names and in January, he was reunited with fellow La Masia player Gerard Deulofeu.
"Of course, I was with him in Barcelona for two years. Of course, now he is here with us and it is great. I am very happy to see him and hopefully we can do great things together."
Watford could secure their highest ever Premier League finish with a win over Manchester United on Sunday.