Middlesbrough's Hayden Hackney scores their first goal [Source: Reuters]

Chelsea suffered a surprise 1-0 loss at second-tier Middlesbrough in the first leg of their League Cup semi-final with Hayden Hackney’s goal giving Mauricio Pochettino’s wasteful side plenty to do in the return.

The 21-year-old Hackney’s silky finish from an Isaiah Jones pass stunned the visitors in the 37th minute at the Riverside Stadium and the hosts defended superbly to take a slender advantage to Stamford Bridge.

Chelsea only had themselves to blame though as they dominated possession but squandered a host of chances — the biggest culprit being Cole Palmer who failed to hit the target twice in the opening half with the goal gaping.

Boro, who won the trophy in 2004 but are currently 12th in the Championship, had chances on the counter-attack to increase their lead but will still head to London believing they can reach Wembley.

Chelsea’s players were booed by some of their own fans at the final whistle with Thiago Silva acting as peacemaker but they will be confident of making amends in the second leg on Jan. 23. Liverpool host Fulham in the first leg of the other semi-final on Wednesday.

Chelsea’s stuttering first season under Pochettino has been a case of one step forward and two back and Tuesday was a prime example of the problems they face as they were unable to beat Michael Carrick’s injury-ravaged Boro.

They had 18 goal attempts, the majority in the first half, but once again they lacked quality in front of goal and were often exposed in defence.