Alli’s international activity was restricted to just 22 minutes as a substitute in Amsterdam on Friday and he was the shock omission from the 16 players who got onto the Wembley pitch in Tuesday’s 1-1 draw with Italy.
In his absence, Southgate has praised the understanding developed between Jesse Lingard and Raheem Sterling just behind the central striker.
After Tuesday’s match, the England manager was at pains to explain Alli was still an “important player” and has reassured the 22-year-old his place on the plane is not in jeopardy.
Before making his final team selection, Southgate will monitor his performances for Tottenham – particularly in relation to his partnership with Kane.
However, with the latter out until the middle of April at the earliest, it leaves at most five Premier League games for Alli to prove he is still the best option to play alongside the England and Tottenham talisman.
“I can only pick 11,” Southgate explained. “We have great competition for places but he is well in that mix and his relationship with Harry, is of course, a really important factor in that.
“That is one of the big things about being an England manager, you will have decisions to make.
“Dele is well in the frame and there is no reason he cannot come to Russia and have an impact on that tournament. We have seen the ability he has. I am looking forward to watching him over the next few weeks.”
Southgate claimed he had planned to give Alli at least a cameo, before a late injury to John Stones disrupted those plans. Furthermore, the Three Lions boss was at pains to insist he was not trying to deliver any sort of message with the international snub.
“There is no ulterior motive for leaving him out,” he said.
FIFA regulations insist Southgate submits a “release list” of 35 players on May 14 – the day after the Premier League season finishes. The “final list” of 23 names must be chosen from those by June 4.
However, Southgate has indicated he will announce his 23 at the earliest possible opportunity after the English club season ends, with just a handful of additional players put on standby in case of injury.