Royals in friendly action tonight
The Royals midfielder was regularly part of the national set-up before suffering injury earlier this season, but is now determined to stake a claim for the upcoming World Cup in Brazil.
"Every player wants to play in the Premier League and the World Cup - I am no different," Williams said in February.
"If I can achieve both, I could easily look back and say the year 2014 was the best year of my life. It would mean everything to me.
"When you have the opportunity to play at the World Cup you have to do everything possible to be included. I will do everything in my power to show my ability to play in the US team by helping Reading achieve promotion."
Welsh duo Chris Gunter and Hal Robson-Kanu are also on international duty this week, as they take on Iceland at home on Wednesday.
On the same date, Garath McCleary will be representing the Royals for Jamaica in their game with St. Lucia, with Jobi McAnuff withdrawn after picking up a knock in training.
Latvia captain Kaspars Gorkss has a game with Macedonia on the horizon, while Alex Pearce and Stephen Kelly have been called up for Republic of Ireland's friendly with Serbia in Dublin on Wednesday night.
Another man representing the Emerald Isle is Pierce Sweeney. Fresh from collecting his FAI U19 player of the year award, the 19-year-old defender is in the U21s ROI squad for their home game with Montenegro.
Goalkeeper Jonathan Henly is another of our U21s player called up, he's involved with Scotland for their home match with Hungary.
In our Academy, Sammi Fridjonsson scored for Iceland's U19s in a 3-0 win over Scandinavian rivals Sweden in a friendly on Tuesday, and will also play against them on Thursday.
Elsewhere George McLennan and Jake Sheppard have received Scotland U19 and U17 calls respectively, Lewis Collins has been duty for Northern Ireland U19s, and Bogdan Vastsuk was called up for Estonia U21s.