The visitors had been cruising towards successive league wins for the first time since September after Dwight Gayle ended his 14-game goal drought by scoring twice before the interval.
Having spurned the two opportunities, Newcastle found themselves in a state of panic after Smith halved their lead, and Gosling was left unmarked as he fired home in the 89th minute.
"Almost everybody is available apart from Jesus Gamez, and Slimani had a set-back the other day, so he will not be available", Benitez told reporters ahead of Newcastle's league trip to Bournemouth on Saturday.
DAN GOSLING haunted former club Newcastle with a last-minute equaliser for Bournemouth.
We all know Benitez as a manager that prefers to keep his players, supporters and the opposition second-guessing his lineups, one that would be unperturbed about altering a team that defeated the current second best club in the Premier League.More news: Child dies of flu; 2nd this season in Mississippi
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"Everybody is disappointed, especially him (Shelvey)".
"We had to manage things better, although it was hard because they were pushing and making crosses from everywhere".
He said: "Dwight was complaining about a little bit of tightness in his hamstrings, so we needed to make a substitution".
"We were really pleased with the first half and even at the start of the second half, but when we conceded the goal, we lost the composure and control".
"You saw from us, when we beat Chelsea, it gave everyone a spring in our step, a real confidence we can compete with anyone in the division. We did a lot of things right, but we didn't win the game". It is not easy to defend when they are attacking and attacking though, and it is hard to do everything ideal.