Diame had an deflected shot saved seconds after coming off the bench against Liverpool at the weekend.
The midfielder was sent on at St James’s Park in the 90th minute by Rafa Benitez with the game level at 1-1.
Liverpool failed to deal with a corner and a weak shot from Diame took two deflections – the second off Dejan Lovren’s arm – before it was gathered by Simon Mignolet.
Diame is yet to start a Premier League game this season, with Benitez having preferred Ayoze Perez at No 10 up to now.
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And the 30-year-old – who retired from international football earlier this year to concentrate on his club career – knows he must take every opportunity that comes his way.
“The defender deflected, and made a penalty as well,” said Diame. “I had this chance. I played only three minutes, in football things can change quickly. You just need to be ready.”
Diame, however, was happy with the result overall – and the “fighting spirit”of the team – against a talented Liverpool side.
Joselu claimed a point for United by cancelling out Philippe Coutinho’s stunning opening goal before the half-time break.
“We’re very pleased,” said former Senegal international Diame. “When you play at home, you always want to win, but against Liverpool, it’s a good point.
“The fighting spirit we showed is good for the future.”
Benitez and his players worked on a plan for the game all week – and Diame felt it worked.
“We were working all week about the shape of the team,” he said.
“The manager gave us some tactics. We can see that this helped us a lot. We just need to keep going and keep fighting.”
Ninth-placed United have taken 10 points from their first seven games.
“It’s a good start,” said Diame. “When you come back from the Championship, and you start a season like this, I think it’s always good for the future.
“We just need to keep going and keep working.”
Diame believes Newcastle have adjusted well to the Premier League following their promotion from the Championship.
“The quality is the difference (to the Championship),” said Diame. “You saw the goal of Coutinho. They are massive players.
“They run quicker and they are more organised. You just need to make the step up.”
United return to action on October 15 at Southampton’s St Mary’s Stadium.
And Diame doesn’t necessarily think the international break has come at a bad time.
“I think when you do well, and you’re happy with your performances, it (the international break) doesn’t matter,” he said.
“(But) when you’re in a bad mood, it’s difficult to wait to weeks to play a game.”