# Enter your code here. Read input from STDIN. Print output to STDOUT
q = int(raw_input())

for i in range(q):
    onEdge = "NO"
    maxx,maxy = 0,0
    listx,listy=[],[]
    n = int(raw_input())
    for j in range(n):
        x,y = map(int,raw_input().strip().split(' '))
        listx.append(x)
        listy.append(y)
        if (x >0 ) and (y >0) :
            if x < maxx :
                break
            if y < maxy :
                break
        maxx = max(listx)
        maxy = max(listy)
        if j == n-1 :
            onEdge = "YES"
    print onEdge