Chelsea have got themselves into all manner of difficulties in defence this season, trying a whole host of combinations with little success.
One option they have rarely used has been left-back Baba Rahman, who had become virtually a forgotten man despite arriving at Stamford Bridge from Augsburg in a £21.7 million deal in the summer.
Rahman has started only one Premier League match - Chelsea kept a clean sheet and triumphed 2-0, albeit at home to a struggling Aston Villa.
You don't command a fee of £21.7m without being a good player, and the 21-year-old showed encouraging signs against Dynamo Kievon Wednesday night.
Rahman was bright from the start, using the ball well and getting forward whenever possible.
He provided the natural left footed attacking option at left-back that they haven't always had since Ashley Cole faded, allowing Cesar Azpilicueta to switch to his most natural position of right-back and Kurt Zouma to switch to his most natural position of centre-back. Round pegs in round holes, and Chelsea looked more balanced.
Rahman's attacking instincts meant that Kiev's Andriy Yarmolenko - a summer target for Everton - was forced on to the defensive and rendered ineffectual in the first half.
The highly-rated winger improved after the interval, causing some problems, and defensively there are still some areas for Rahman to work on.
But the Ghanaian completed 3 out of 3 tackles and was successful with 45 of 51 passes - second only to Nemanja Matic. A total of 13 came in the attacking third, only bettered by Cesc Fabregas and Oscar.
Rahman also made 10 ball recoveries, more than anyone else on the pitch.
Given Chelsea's recent problems in defence, he has surely made a strong case to start again in Saturday's Premier League game at Stoke.