#include <bits/stdc++.h>
using namespace std;
long long mod = 1e9 + 7;
long long mod2 = 123;
const long long N = 5e5 + 10;
void solve() {
  int n;
  cin >> n;
  pair<long long, long long> x[n];
  for (int i = 0; i < n; i++) cin >> x[i].first >> x[i].second;
  for (int i = 0; i < n; i++) {
    if (x[i].second > x[i].first) {
      cout << "NO";
      return;
    }
    if (i == 0) continue;
    if (x[i].second < x[i - 1].second || x[i].first < x[i - 1].first) {
      cout << "NO";
      return;
    }
    if (x[i].second - x[i - 1].second > x[i].first - x[i - 1].first) {
      cout << "NO";
      return;
    }
  }
  cout << "YES";
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  int t = 1;
  cin >> t;
  for (int i = 1; i <= t; i++) {
    solve();
    cout << "\n";
  }
  return 0;
}
