With the score at 2-2 and 86 minutes on the clock, the Newcastle forward rushed back to prevent Shinji Okazaki from scoring what would have been a certain victor.
Newcastle will now turn their attention to a crucial Premier League fixture against Everton this Wednesday evening at St James' Park.
"We have to learn and have more experience and manage it better. It is sometimes a lack of experience", the Spaniard told BBC Sport.
"I thought we were in control at 2-2, and I thought it could be easier to score for us than them, but then another mistake and a counter attack and we concede".
The Premier League reportedly advise that any takeover deal could take up to 30 days to clear the required paperwork to officially seal the deal, although the Christmas period could see that extended. We have to improve the things we are not doing well at the moment. The defeat marks seven games without a win - a run of results that has the Championship winners worrying that they may be seeing that division a lot sooner than expected.
The defeat means that Benitez has now lost three Premier League home games in a row for the first time in his managerial career.
You can get away with having a couple of players who aren't really good enough but not half a dozen. The first half was good but the beginning of the second half was hard.
Alan Shearer can't wait to see the back of Mike Ashley and until that happens, hard to see anything positive ahead.
Such positivity was not associated with Puel's Southampton during his one-season reign last term, despite guiding the Saints to the EFL Cup final.