Harry Kane moved within one of Jimmy Greaves' Tottenham goalscoring record with a trademark finish to earn Spurs a safe FA Cup passage against Portsmouth.
Moments after Emerson Royal's header hit the post, Kane exchanged passes with Ryan Sessegnon before curling into the far corner from 18 yards.
Kane has now scored 265 Spurs goals, one behind the legendary Greaves.
Oliver Skipp fired over a great chance to add a second goal but the League One visitors had no reply to Kane's strike.
With Dejan Kulusevski, Richarlison and Lucas Moura among a growing Spurs injury list, Antonio Conte was forced to start Kane and Son Heung-min in a strong forward line despite making eight changes overall.