Defending champions Chelsea were taught a harsh lesson as Women's Super League leaders Manchester City took a huge step towards claiming the title with a 5-1 victory over the Blues on Sunday. Kerolin struck an impressive hat-trick while Khadija Shaw and Vivianne Miedema also got in on the act, with Alyssa Thompson merely able to register a consolation which did little to change a devastating result for Sonia Bompastor's side.It would take just 13 minutes for the deadlock to be broken by City, as Kerolin netted with a deflected strike after Naomi Girma failed to deal with a cross from the right. Chelsea did have the ball in the net at the other end soon after as Wieke Kaptein headed home Lauren James’ delivery, albeit from a marginally offside position.Sandy Baltimore began to come into the game on the left and created a couple of dangerous situations, whistling a powerful strike just past the post while her incisive pass saw Erin Cuthbert have a shot tipped over the bar. Keira Walsh also came close twice with near-identical strikes from the edge of the box after a corner. But with less than 10 minutes to go until half-time, City doubled their lead through Shaw after Kaptein lost the ball in the midfield. Shaw was far too strong for Girma, who she shrugged aside to bound through on goal and clip the ball over the onrushing Hannah Hampton.Kerolin saw an audacious back-heeled attempt slip wide of the post just before the break, but would take the game beyond the visitors with a masterclass in finishing after the break. The 26-year-old Brazilian had the freedom of the Chelsea half to run through on goal and scoop the ball into the net for her second, before she completed her hat-trick on 54 minutes after a Hemp assist.Kaptein was gifted a chance to get Chelsea on the scoresheet but could only shoot over the bar when through on goal, though the Blues would soon score through Thompson, who netted with a powerful strike from outside the area that gave goalkeeper Ayaka Namashita no chance.But any hopes of a route back into the game were quickly quashed as Miedema rose highest from a corner and headed into the far corner of the net. Chelsea had been well beaten and could have no complaints about the nature of the scoreline in the end.GOAL rates Chelsea's players from Etihad Stadium...Hannah Hampton (4/10):The England shot-stopper did not cover herself in glory for Karolin's third goal but was not given much of a chance by the players in front of her. She will still feel as though she could have done more.Naomi Girma (3/10):The American international was at fault for both of City's first two goals and was no match for the powerful Shaw. Her performance summed up a poor defensive display by the visitors.Millie Bright (5/10):The Blues skipper did her best to lead her troops but could do nothing to prevent City from a rampant victory.Veerle Buurman (4/10):Could not stop Kerolin and was taken off by Bompastor early in the second period as the Blues changed formation.Ellie Carpenter (4/10):Struggled at times against Hemp and was caught out of position for Kerolin's hat-trick. Showed industry but was outdone by her opposite number on the day. Keira Walsh (5/10):Provided a surprise attacking threat for the Blues with her shooting from the edge of the box. Could do nothing to control the game in midfield, though.Erin Cuthbert (4/10):Had one well-struck shot saved but was sacrificed early in the second period after failing to put her stamp on the game.Wieke Kaptein (3/10):Lost the ball far too easily for the second goal and allowed Miedema a free header which she was not going to pass up. The 20-year-old looked far out of her depth in midfield and lost the ball on multiple occasions, while seeing a goal disallowed for offside.Sandy Baltimore (5/10):Probably Chelsea's biggest threat in the first half, the wing-back was dangerous in attacking areas but did not do enough to stop Kerolin defensively.Lauren James (4/10):Played in a nice cross for Kaptein's offside goal but otherwise failed to impact proceedings. A slice out of play by her own corner flag summed up her day.Alyssa Thompson (6/10):Took her goal well despite a quiet afternoon. Cannot really be blamed for her side's defensive woes, though.Add GOAL.com as a preferred source on Google to see more of our reportingSam Kerr (4/10):Played almost the entire second half but failed to change the game after her introduction.Sjoeke Nusken (5/10):Quiet display off the bench and could not turn the tide in midfield.Johanna Rytting Kaneryd (5/10):Replaced James and had little more of an impact in attack.Aggie Beever-Jones (N/A):Came on for Walsh towards the end.Sonia Bompastor (4/10):The Chelsea boss saw her side all-but concede the WSL title this afternoon. Second best in every department, the Blues' changes did nothing to alter the outcome and Bompastor will be forced to go back to the drawing board.