Sidwell then played in the 2007 FA Community Shield where Chelsea lost on penalties to Manchester United. His league debut for Chelsea came on 12 August 2007 in a 3–2 victory against Birmingham City when he replaced Florent Malouda in the 83rd minute. He scored his only goal for the club on 26 September 2007, in a 4–0 win away to Hull City in the third round of the Football League Cup. Sidwell struggled to establish himself in Chelsea's first team under José Mourinho and made a total of 25 appearances in 2007–08. At the end of the season, Sidwell became linked to several Premier League clubs, including Everton, Aston Villa and Middlesbrough. Aston Villa On 10 July 2008, Sidwell signed a three-year deal with Aston Villa for an undisclosed fee, believed to be in the region of £5m. He made his debut for the club in a pre-season game against FC Zürich, playing the first 45 minutes, in a match which Villa lost 2–1. Sidwell scored an own goal on his competitive debut for Villa on 19 July 2008 in a 2–2 draw with Odense BK in the UEFA Intertoto Cup. Villa won the second leg 1–0 to progress in Europe but Sidwell picked up a calf injury. He returned to action against Stoke City Reserves on 3 September 2008 but then picked up a knee injury. Sidwell eventually played his first Premier League game for Villa on 26 October 2008 where he came on as a substitute and scored in a 4–0 win away at Wigan Athletic. On 9 November 2008 Sidwell scored against Middlesbrough but then gifted Tuncay a late goal with a poor back pass as Villa lost 2–1. He was backed by Villa captain Martin Laursen to move on from his mistake. Sidwell scored his third goal of the season just 34 seconds into against Everton on 7 December 2008, Villa went on to win 3–2. Sidwell was sent-off against Hamburger SV in the UEFA Cup on 17 December 2008 for two-bookable offences. Sidwell picked up a hamstring injury against CSKA Moscow on 26 February 2009. His injury kept him out until the final match of the season against Newcastle United on 24 May 2009. In total Sidwell played 25 times in 2008–09 as Villa finished in 6th position. Villa had a mixed start to the 2009–10 season as they were knocked out of Europe