Chesterfield condemned Blues to their sixth defeat of the season as the Spireites ran out 4-0 winners at Roots Hall.
A Danny Rowe brace in the first half was added to early after the break by Saidou Khan, before Rowe completed his hat-trick from the penalty spot which sealed Chesterfield’s sixth win of the season.
Phil Brown made one enforced change to his starting line-up from the team that beat Eastleigh last time out, with Simeon Akinola picking up a knock in that game on Tuesday which forced him to miss out.
On loan forward Benji Kimpioka took Akinola’s place, the 21-year-old forming a very young partnership alongside 19-year-old Hamzad Kargbo who retained his spot from Tuesday's win over the Spitfires.
After a cagey opening quarter of an hour the visitors took the lead with the game’s first chance, Rowe finding the bottom left-hand corner of the net from 20 yards in the 19th minute.
Kimpioka then almost provided an immediate response as he raced through and got beyond Chesterfield goalkeeper Scott Loach, but the ball held up after the two players came together and the Spireites were able to clear the danger before Kimpioka could latch on to the loose ball.
In the 36th minute Rowe, looking for his second goal, weaved through the Blues defence but took one touch too many as he got inside the penalty area which allowed for Jason Demetriou to track back and make an interception before he could get a shot off.
Four minutes later, though, he made amends to notch his and Chesterfield’s second of the afternoon.
Collecting a cross at the near post, the 32-year-old former Bradford striker swivelled and fired past Steve Arnold at the near post to double Chesterfield’s advantage going into half time.
Brown opted for changes during that 15-minute interval with both Rhys Murphy and Terrell Egbri coming on, replacing Kargbo and Kimpioka. And it almost paid immediate dividends as Blues' number nine latched on to James Dunne’s clever free kick, but the summer signing poked the ball wide of the near post.
And a matter of minutes later Chesterfield added a third after a clever move. It once again involved Rowe as he fed Jeff King, whose cross to the back post was turned home by Khan.
Rowe dragged an effort wide as he attempted to get a hat-trick midway through the second half, but in the 73rdminute the opportunity presented itself from the penalty spot for him to make up for that after a collision in the Blues box between Ralph and Kabongo Tshimanga. Referee Scott Tallis pointed to the spot and Rowe stepped up and powered the ball down the middle for his third of the afternoon.
That then sparked a group of home supporters to charge on to the pitch in protest which brought about a prolonged break in the game, and when the game eventually got back underway it was Chesterfield who went closest to add to the scoreline as a shot was cleared off the line by Ralph and then Laurence Maguire’s header was also turned away by Charlie Sayers from underneath the crossbar.
King then had a shot pushed to safety by Arnold and it remained 4-0 to the visitors, a reverse of the scoreline when the two sides last met back in April 2017.
Blues XI: Arnold, Ralph, Hobson, Bridge, Dunne (C), Ferguson, Atkinson (Dalby 61'), Sayers, Kargbo (Murphy 45’), Demetriou, Kimpioka (Egbri 45’). Subs Not Used: Howard, Walsh
Chesterfield XI: Loach, Miller, Gunning (C), Maguire, Rowe, Weston (Oyeleke 68’), Kellermann, Tshimanga, King, Khan (Mandeville 66’), Kerr (Grimes 32’). Subs Not Used: Tyson, Whittle
Referee: S Tallis
Assistants: J Block & C Myatt
Fourth Official: C Martland
Southend United: None
Chesterfield: Rowe 19’ 40’ 73', Khan 49’
Attendance: 4,625 (375 Away)