So clumsy were both that Spurs boss Mauricio Pochettino would have been forgiven for leaving him out this weekend after bringing in Davinson Sanchez in the midweek Champions League victory over PSV Eindhoven.
He kept faith with his compatriot, however, and found the Foyth was very much with him this time out as his header compounded Palace’s miserable home record this campaign.
This made it six games with no wins and, alarmingly, no goals.
And few among the home fans would have expected any different as they filed in to Selhurst Park to find Wilfried Zaha had not made the matchday squad.
Zaha sustained a hamstring injury in the 3-1 defeat by Chelsea last Sunday and, while Roy Hodgson had hoped he would recover in time, it wasn’t to be.
Spurs boss Mauricio Pochettino, meanwhile, made six changes to the side which beat PSV Eindhoven 2-1 with Harry Kane’s late double in midweek.
That meant a first Premier League start of the campaign for Victor Wanyama, who settled into defensive midfield alongside Moussa Sissoko.
The visitors started the game well but Palace settled and for a good period in the first half they looked the more likely to score.
Cheikhou Kouyate launched himself acrobatically at James McArthur’s header back across the box but Lucas Moura averted the danger with an important header.
Andros Townsend got in round the back of Foyth to latch on to Mamadou Sakho’s ball over the top but, from a tight angle, he drilled his effort into the nearside netting of Wayne Hennessey’s goal.
Foyth appeared to have the jitters again when he tried to pass a ball back to keeper Hugo Lloris but instead played it straight out for a corner with the keeper in an altogether different postcode.
Credit to Foyth, some players would have gone into their shell at that, but there he was just a couple of minutes later demanding the ball again.
Spurs were on the back foot but for all Palace’s good work, as you’d perhaps expect from a side struggling for goals, Lloris was never troubled.
Sissoko danced away from two or three challenges at the other end before a good run ended with a shot which was blocked at close range.
Then Davies did well to get to the byline and a fine, full-bodied cross deserved a better header from Alli.
The England midfielder had much more time and space than he realised and ought to have at least forced a save, but instead his effort was harmlessly wide.
It was Spurs’s turn to enjoy the lion’s share of possession and Kane’s 25-yard strike forced a decent save from Hennessey after Luka Milivojevic had lost possession.
Palace created the first opening after the break with James Tomkins nodding wide at the far post from Milivojevic’s centre.
Tomkins didn’t last much longer before limping off and soon after his departure Palace found themselves behind.
Kane met Erik Lamela’s corner, which Milivojevic blocked, and and as the ball sat up nicely Foyth threw himself at it to power home.
What a moment it was for the 20 year-old and, after last week’s display, no wonder he celebrated with so much gusto.
What a blow it was for Palace as well and Roy Hodgson must have feared his side would struggle to get back into the game given they can’t buy a goal at home.
They certainly had the chances, though, and were only denied by some fine goalkeeping by Lloris.
First he saved well from Jeffrey Schlupp’s long-range effort and as the Palace star tumbled on to Lamela, he caught the Argentinian and opened up a nasty gash on his forehead which led to the Spurs man’s substitution.
Townsend failed to get hold of another good late chance and when another Eagles substitute, Alexander Sorloth, forced another fine save out of Lloris, the home side knew that, once again, it wasn’t to be their day here in south London.