Better way of handling Collectors.groupingBy in Java

Question

I have this json for student marks and I want to get the Student(s) with highest totalMarks from each standard...I have written this code which is giving the solution but I am not liking the 2 step process. Requesting suggestions to optimize this code to a 1 step solution. Thanks in advance...

json

{
  "students": [
    {
      "fullName": "Student 1",
      "standard": 10,
      "rollNumber": "1R",
      "house": "Red",
      "marks": {
        "maths": 90,
        "english": 90,
        "science": 80,
        "history": 90
      },
      "totalMarks": 350,
      "sports": [
        {
          "sportName": "karate",
          "status": "purple-belt"
        },
        {
          "sportName": "swimming",
          "status": "swimmer"
        },
        {
          "sportName": "karate",
          "status": "green-belt"
        }
      ],
      "hobbies": [
        "programming",
        "reading"
      ]
    },
    {
      "fullName": "Student 2",
      "standard": 10,
      "rollNumber": "2R",
      "house": "Blue",
      "marks": {
        "maths": 90,
        "english": 90,
        "science": 90,
        "history": 90
      },
      "totalMarks": 360,
      "sports": [
        {
          "sportName": "cricket",
          "status": "all-rounder"
        }
      ],
      "hobbies": [
        "gaming"
      ]
    }
}

Code

 Map<Integer, List<Student>> map8 = reportCard.getStudents().stream().collect(Collectors.groupingBy(Student::getStandard));
        map8.keySet().forEach(key -> map8.put(key, map8.get(key).stream().reduce((st1,st2) -> st1.getTotalMarks() > st2.getTotalMarks()? st1:st2).stream().toList()));
        map8.forEach((key, value) -> System.out.println(key + "-" + value));

As I said I would like to have this in a single step. Please suggest.