Siem de Jong believes Newcastle United must "strengthen" in the summer so that both the Dutch midfielder and the rest of the squad can "forget about this year". The 26-year-old attacking-midfielder made a goal-scoring return from his long injury lay-off on Saturday as he came off the bench to net in the 3-2 defeat against Swansea City - and he then completed 90 minutes for the Newcastle Under-21 side against Derby County on Tuesday night. With a torn thigh muscle and then a collapsed lung having made this the "worst season" of De Jong's career, the Magpies themselves have also had a campaign to forget - tumbling down the Premier League following seven straight defeats. They now sit just five points above the relegation zone with four games remaining, and De Jong knows additional faces must be brought in this summer as the club rebuilds. Speaking to The Mirror, De Jong said: "I want a totally different season for me and the team next year. The team will change over the summer with some players leaving and new ones coming in. "We need to strengthen and everybody knows that. I want to forget about this year and show that I can be a big player for Newcastle." It appears as if Newcastle's rapid descent down the Premier League table has also taken De Jong by surprise, with the six-cap Dutch international explaining that he did not expect to be fighting at the wrong end of the division following his £6 million move from Ajax last summer. He continued: This has been the worst season of my career and its been very difficult. When you come to a new club, you want to prove yourself to the team and fans straight away but Ive not been able to do that. For all the latest NUFC News, Views and Transfers make sure to follow WhatCultureNUFC on Twitter and Facebook.