The English Premier League has seen a flurry of activity in the current transfer window as managers look to strengthen their squads prior to the season's kick-off on August 15. Hitting the headlines have been Manchester City's huge spending spree and Cristiano Ronaldo's departure from Old Trafford to join Brazilian sensation Kaka as blockbuster new signings at Real Madrid. Manchester City have been the biggest spenders in the Premiership by buying up, among others, Carlos Tevez, who was previously at local rivals Manchester United. Also adding Gareth Barry, Emmanuel Adebayor and Roque Santa Cruz have taken City's spending to an estimated Â£80 million this summer. However, manager Mark Hughes is not finished in the transfer market and is now looking to bolster his defence. With approaches on Chelsea's John Terry rejected, attention has now turned to Arsenal's Kolo Toure, and Everton's Joleon Lescott. Elsewhere, with the departure of Ronaldo and Tevez from Manchester United, Sir Alex looked to shore up the team's front line. Injury-plagued Michael Owen, Antonio Valencia and Gabriel Obertan were all snapped up by the Premiership title holders. However, questions remain as to whether such signings are sufficient replacements for Tevez and (even more so) Ronaldo. In another interesting deal that broke the record for Russia's most expensive player, Yuri Zhirkov of CSKA Moscow moved to Chelsea. Although the fee remains undisclosed it was believed to be in the region of Â£18m. The Blues have also signed keeper Ross Turnbull and 19-year-old striker Daniel Sturridge. English international Glen Johnson left Portsmouth for Liverpool, who had to fight off interest from Chelsea and Man City to secure the full back. In Arsenal's only signing of the summer so far Ajax's captain, Thomas Vermaelen, made a Â£10m move to the London club. As the Tottenham squad prepared for takeoff to their pre-season tour of China on Monday, Darren Bent was taken from the plane. Talks with Sunderland about a move to the club had come closer to fruition, in a deal said to be worth Â£12m. Following Peter Crouch's Â£9m homecoming move to Tottenham, Bent's services were now considered surplus and sale was inevitable. Bent was not the only player, however, to miss the flight, as Jermain Defoe was mistakenly arrested whilst driving to the airport. Police wrongly believed he was banned from the roads due to a computer error. Dubbed 'the next Patrick Viera', 20-year-old Steven Nzonzi of France was purchased by Blackburn Rovers for an undisclosed fee. Experienced midfielder, Sean Davis transferred from Portsmouth to Bolton on a free loan, with Portsmouth losing out on Â£3m that was offered for Davis in the mid-season transfer window. Following Middlesbrough's relegation to the Championship, Stewart Downing departed for a sizeable Â£12m to Aston Villa. In Spain, Real Madrid have hit the headlines this summer with three astronomical signings. Kaka was purchased from AC Milan for a reported Â£56 million. This was shortly followed by the record-breaking signing of the sensational Ronaldo, for Â£80 million, from Manchester United, raising the sporting world's collective eyebrows. Lyon's Karim Benzema was also purchased by Madrid for Â£30m, the young striker showed his worth by scoring the winning goal in his debut versus Shamrock Rovers. Madrid's rivals, Barcelona, determined to not be left behind signed Zlatan Ibrahimovic from Inter Milan for Â£40m alongside sending Samuel Eto'o to the Italian club. The transfer window closes on the August 31, leaving a month left in which we are sure to see plenty more movement across the Premier league and the rest of Europe.