Brooklyn Decker and Andy Roddick
Brooklyn Decker and Andy Roddick are expecting their first child after six years of marriageGetty

American fashion model and actress Brooklyn Decker is expecting her first child with husband, former American professional tennis player Andy Roddick.

The 28-year-old Just Go With It actress announced the news on her Instagram account.

"So this happened... #the3ofus," Decker captioned the image, showing off her growing baby bump.

However, People magazine accidentally congratulated Wimbledon champion Andy Murray who recently tied the knot with his long-time girlfriend Kim Sears, instead of Roddick.

The world number three exchanged vows with Sears on 11 April at the 12th century Dunblane Cathedral in his hometown of Dunblane, Scotland.

"Not sure my wife and @andyroddick will be best pleased to find these out via Twitter! #error," Murray jokingly tweeted.

"Congrats to the real parents @andyroddick and @BrooklynDecker," he added.

Decker married Roddick in 2009 at their home in Texas, after being engaged for a year.

Last year in April, the Grace And Frankie actress expressed her love for children.

"It is great getting to be Aunt Brooklyn and play with my friends' kids," Decker told People.

"I love seeing Majandra [Delfino] with her daughter, but she would also get jealous any time I told her I was going home and having a wine date with my husband," she added. "I love kids. I definitely want kids. I just have to figure out the timing of that."

So this happened... #the3ofus

A photo posted by Brooklyn Decker (@brooklynddecker) on