Polish star Piotr Protasiewicz and Australian racer Darcy Ward have declined their invitations to participate full-time in the 2012 FIM Speedway Grand Prix series.Sweden's Peter Ljung will replace Protasiewicz and the replacement for Ward will be announced at a later date.After his girlfriend Jessica gave birth to their son Eddie on Wednesday, the 29-year-old was over the moon to receive a phone call on Thursday offering him the chance to race with the sport's biggest names. And Ljung admits it was the best day of his life.He said: "It's pretty overwhelming at the moment. In a way, although this opportunity was handed to me, I think it was just my turn to have a bit of luck for once."I've broken my legs, feet, hands and have lost quite a lot of time over the years I've been riding. Now the wind has changed a bit and I just got a bit of luck for once."It has been a lot to handle in a couple of days, but I don't think I've ever had a better 24 hours - definitely not."My girlfriend is still in hospital and I've got my daughter Iza at home with me. We've been going back and forward to the hospital and exchanging phone calls. I've got a lot of emotions going through my head, but this is amazing."I'm not going to apologise for having this handed to me. I just think it was my turn to have a bit of luck. It's going to be really, really interesting and fun."As well as looking after his young family, Ljung has just a few months to get ready for the season-opening FIM New Zealand Speedway Grand Prix at Western Springs Stadium in Auckland on March 31.The Vastervik and Grudziadz rider says he has started work today on getting his SGP set-up in place.But asked whether he had a target for his first full season in the Grand Prix series, Ljung was not keen to set one just yet.He said: "I'm just taking it all in right now and I think we're just going to try and do it the best we can."I don't think we'll say we have a target to do this or that. This is just the first year and I've got to do the best I can and have a lot of fun along the way. We'll see what happens as the season goes on."There's going to be quite a few things to sort out and I started today. I've started to make some phone calls and I sat down with my brother for quite a while to decide how we're going to approach all this."We've got a bit less time than we wanted to prepare it, but we've still got a good few months, so I hope it will come good in the end. We'll just do it the way we think is right because it's quite personal how you deal with it all and approach it."Ljung made his SGP debut in the FIM Scandinavian Grand Prix at Gothenburg's Ullevi Stadium on August 30, 2004, scoring seven points.He is excited about the prospect of racing in the big SGP events beyond Sweden's borders and cannot wait for the FIM Dansk Metal Danish Grand Prix in Copenhagen's PARKEN Stadium on June 9 and the FIM British SGP in Cardiff on August 25.He added: "I'm looking forward to all of them. I've been to Copenhagen quite a few times to watch the GP and the atmosphere is fantastic. I've always thought 'I want to do that meeting' and the same with Cardiff."I've only been there once, but that was unreal. This is a dream come true to get this opportunity."I've just got to suck it in, enjoy it as much as I can, but hopefully I can get some decent results and score some points as well."