Coronation Street‘s Tracy McDonald throws her estranged husband Steve a surprise birthday party next week – only to find out that he and Cassie Plummer are now officially an item.

As Steve pushes forward with his divorce from Tracy, it turns out he has good reason to want to formalise their split.

But with Tracy not Cassie’s biggest fan, how will she react when she walks in on the pair together?

“Cassie the worst person on the Street that Steve could hook up with,” our Corrie source says.

“Plus, now that Tracy’s ex Tommy O is well and truly out of the picture, it’s clear she’s been dragging her feet on the divorce. Tracy has a habit of wanting what she can’t have, so could this change her mind over her feelings for Steve?”

When Steve puts pressure on Tracy to check over the divorce papers, she suggests they meet in the pub to discuss them.

However, it’s all a ruse to distract him from the matter at hand as she turns the meeting into surprise birthday drinks for her estranged hubby.

Steve’s not impressed and makes a swift exit. Tracy follows him with Amy in tow, but the pair are in for a shock when they walk in on Steve and Cassie canoodling.

Later, Steve tells Cassie that as far as he’s concerned they are an item, and he seals the deal by planting a kiss on her in the middle of The Rovers.

But how will Tracy feel about the romance – and is she set to make life difficult for the new lovebirds?