The only other option Southgate is considering is whether he sacrifices one of his three attacking players behind Harry Kane, to bring in Eric Dier alongside Henderson, as he did for friendlies against the likes of Germany, Holland and Italy.
Hosts Russia, the lowest ranked team in the tournament, scored five of their 11 goals from set-pieces on the way to the quarter-finals, their strongest showing since the end of the Soviet Union, and got past highly fancied Spain in the last 16 thanks to a penalty shootout.
"We're going to have to pay attention to those details, because we conceded a goal against Russian Federation that we shouldn't allow".
"But any team in a World Cup semi-final is going to find the energy and going to find the motivation".
Modric is Croatia's creative fulcrum and the effectiveness of the Real Madrid playmaker in Moscow will be integral to his nation's hopes of reaching the World Cup final for the first time. It's important that we do our best on the pitch.
But he is certainly well aware of the threat that Croatia pose in the centre of the field.
"We watched the game today and saw how good they are from dead-ball situations", captain Luka Modric said.
"They're very risky on set-pieces", said Real Madrid midfielder Modric.
The big Croatian looks likely to shake off the hamstring injury that hampered him against the Russians and would be an imposing figure between the sticks for England's penalty takers if a place in the final came down to spot-kicks.