The team played a high tempo from the first whistle and were rewarded by Gareth's glancing header from Gylfi Sigurdsson's cross to open the scoring with only six minutes on the clock.
It was soon 2-0 as Gylfi followed-up Jermain Defoe's strike and Jan Vertonghen completed the scoring with a bullet header in the second half.
It might have been more but for the form of Inter goalkeeper Samir Handanovic but we have a commanding lead to take to the San Siro next Thursday.
"We played well," said Gareth, who now has 20 goals for us in all competitions this season. "I thought we set the tempo from the first whistle and made it difficult for them. It was a great performance and a worthy result.
"It’s always nice to get a goal. I’m enjoying my football at the moment and it was a great performance. We take a good lead into the second leg with no away goals for them."