#include <bits/stdc++.h>
#define int int64_t
using namespace std;

int32_t main() {
    int t;
    cin >> t;
    while(t--)
    {
        int n;
        cin >> n;
        int x, y, prevx, prevy;
        cin >> x >> y;
        int m1 = x, m2 = y;
        bool ans = (bool) (x >= y);
        n--;
        prevx = x;
        prevy = y;
        while(n--)
        {
            cin >> x >> y;
            if ((x < m1) || (y < m2) || (x < y) || (x - prevx < y - prevy))
                 ans = 0;
             m1 = max(m1, x);
             m2 = max(m2, y);
             prevx = x;
             prevy = y;
        }
        if (ans)
            cout << "YES\n";
        else
            cout << "NO\n";
    }
}